How to make this scary javascript file 'talk' with my page or another jquery file?
<p>I have been battling like crazy with a javascript that allows for infinite scrolling in Tumblr. Call me a newbie but this feels like an old nasty dinosaur compared to what i'm used to with jQuery.</p>

<p>My attempts to make this script talk with my jQuery functions or to recognise DOM elements on the page has proved utterly useless. Since this is the only known working infinite scroll script for tumblr out there, i have to live with it. </p>

<p>I now want to add a spinner that appears when it's loading new content, and hide the spinner when it's not. And also, change the preloader to an "end of posts" message once we reached the end.</p>

<p>Below is the entire script, I'd love if someone could show me how to refer to DOM elements and or .classes and #ids in this page <a href="http://syndex.me" rel="nofollow">http://syndex.me</a></p>

<p>Edit: Please not on the site you'll see a preloader but this isn't 'smart' it's just a div tied to the end of the page.</p>

<pre><code>var tumblrAutoPager = {
    url: "http://proto.jp/",
    ver: "0.1.7",
    rF: true,
    gP: {},
    pp: null,
    ppId: "",
    LN: location.hostname,
    init: function () {
        if ($("autopagerize_icon") || navigator.userAgent.indexOf('iPhone') != -1) return;
        var tAP = tumblrAutoPager;
        var p = 1;
        var lh = location.href;
        var lhp = lh.lastIndexOf("/page/");
        var lht = lh.lastIndexOf("/tagged/");
        if (lhp != -1) {
            p = parseInt(lh.slice(lhp + 6));
            tAP.LN = lh.slice(7, lhp);
        } else if (lht != -1) {
            tAP.LN = lh.slice(7);
            if (tAP.LN.slice(tAP.LN.length - 1) == "/") tAP.LN = tAP.LN.slice(0, tAP.LN.length - 1);
        } else if ("http://" + tAP.LN + "/" != lh) {
            return;
        };
        var gPFncs = [];
        gPFncs[0] = function (aE) {
            var r = [];
            for (var i = 0, l = aE.length; i &lt; l; i++) {
                if (aE[i].className == "autopagerize_page_element") {
                    r = gCE(aE[i]);
                    break;
                }
            }
            return r;
        };
        gPFncs[1] = function (aE) {
            var r = [];
            for (var i = 0, l = aE.length; i &lt; l; i++) {
                var arr = aE[i].className ? aE[i].className.split(" ") : null;
                if (arr) {
                    for (var j = 0; j &lt; arr.length; j++) {
                        arr[j] == "post" ? r.push(aE[i]) : null;
                    }
                }
            }
            return r;
        };
        gPFncs[2] = function (aE) {
            var r = [];
            var tmpId = tAP.ppId ? [tAP.ppId] : ["posts", "main", "container", "content", "apDiv2", "wrapper", "projects"];
            for (var i = 0, l = aE.length; i &lt; l; i++) {
                for (var j = 0; j &lt; tmpId.length; j++) {
                    if (aE[i].id == tmpId[j]) {
                        r = gCE(aE[i]);
                        tAP.ppId = aE[i].id;
                        break;
                    }
                }
            }
            return r;
        };
        for (var i = 0; i &lt; gPFncs.length; i++) {
            var getElems = gPFncs[i](document.body.getElementsByTagName('*'));
            if (getElems.length) {
                tAP.gP = gPFncs[i];
                tAP.pp = getElems[0].parentNode;
                break;
            }
        }

        function gCE(pElem) {
            var r = [];
            for (var i = 0, l = pElem.childNodes.length; i &lt; l; i++) {
                r.push(pElem.childNodes.item(i))
            }
            return r;
        }
        if (!tAP.pp) {
            return;
        }
        sendRequest.README = {
            license: 'Public Domain',
            url: 'http://jsgt.org/lib/ajax/ref.htm',
            version: 0.516,
            author: 'Toshiro Takahashi'
        };

        function chkAjaBrowser() {
            var A, B = navigator.userAgent;
            this.bw = {
                safari: ((A = B.split('AppleWebKit/')[1]) ? A.split('(')[0].split('.')[0] : 0) &gt;= 124,
                konqueror: ((A = B.split('Konqueror/')[1]) ? A.split(';')[0] : 0) &gt;= 3.3,
                mozes: ((A = B.split('Gecko/')[1]) ? A.split(' ')[0] : 0) &gt;= 20011128,
                opera: ( !! window.opera) &amp;&amp; ((typeof XMLHttpRequest) == 'function'),
                msie: ( !! window.ActiveXObject) ? ( !! createHttpRequest()) : false
            };
            return (this.bw.safari || this.bw.konqueror || this.bw.mozes || this.bw.opera || this.bw.msie)
        }

        function createHttpRequest() {
            if (window.XMLHttpRequest) {
                return new XMLHttpRequest()
            } else {
                if (window.ActiveXObject) {
                    try {
                        return new ActiveXObject('Msxml2.XMLHTTP')
                    } catch (B) {
                        try {
                            return new ActiveXObject('Microsoft.XMLHTTP')
                        } catch (A) {
                            return null
                        }
                    }
                } else {
                    return null
                }
            }
        };

        function sendRequest(E, R, C, D, F, G, S, A) {
            var Q = C.toUpperCase() == 'GET',
                H = createHttpRequest();
            if (H == null) {
                return null
            }
            if ((G) ? G : false) {
                D += ((D.indexOf('?') == -1) ? '?' : '&amp;') + 't=' + (new Date()).getTime()
            }
            var P = new chkAjaBrowser(),
                L = P.bw.opera,
                I = P.bw.safari,
                N = P.bw.konqueror,
                M = P.bw.mozes;
            if (typeof E == 'object') {
                var J = E.onload;
                var O = E.onbeforsetheader
            } else {
                var J = E;
                var O = null
            }
            if (L || I || M) {
                H.onload = function () {
                    J(H);
                    H.abort()
                }
            } else {
                H.onreadystatechange = function () {
                    if (H.readyState == 4) {
                        J(H);
                        H.abort()
                    }
                }
            }
            R = K(R, D);
            if (Q) {
                D += ((D.indexOf('?') == -1) ? '?' : (R == '') ? '' : '&amp;') + R
            }
            H.open(C, D, F, S, A);
            if ( !! O) {
                O(H)
            }
            B(H);
            H.send(R);

            function B(T) {
                if (!L || typeof T.setRequestHeader == 'function') {
                    T.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8')
                }
                return T
            }

            function K(X, V) {
                var Z = [];
                if (typeof X == 'object') {
                    for (var W in X) {
                        Y(W, X[W])
                    }
                } else {
                    if (typeof X == 'string') {
                        if (X == '') {
                            return ''
                        }
                        if (X.charAt(0) == '&amp;') {
                            X = X.substring(1, X.length)
                        }
                        var T = X.split('&amp;');
                        for (var W = 0; W &lt; T.length; W++) {
                            var U = T[W].split('=');
                            Y(U[0], U[1])
                        }
                    }
                }

                function Y(b, a) {
                    Z.push(encodeURIComponent(b) + '=' + encodeURIComponent(a))
                }
                return Z.join('&amp;')
            }
            return H
        }

        function addNextPage(oj) {
            if (oj.status == 404) {
                tAP.remainFlg = false;
                return;
            }
            var d = document.createElement("div");
            d.innerHTML = oj.responseText;
            var posts = tAP.gP(d.getElementsByTagName("*"));
            if (posts.length &lt; 2) {
                tAP.rF = false;
                return;
            }
            d = document.createElement("div");
            d.className = "tumblrAutoPager_page_info";
            tAP.pp.appendChild(d);
            for (var i = 0; i &lt; posts.length; i++) {
                tAP.pp.appendChild(posts[i]);
            }
            var footer = $("footer");
            footer ? footer.parentNode.appendChild(footer) : null;
            tAP.rF = true;
        }
        watch_scroll();

        function watch_scroll() {
            var d = document.compatMode == "BackCompat" ? document.body : document.documentElement;
            var r = d.scrollHeight - d.clientHeight - (d.scrollTop || document.body.scrollTop);
            if (r &lt; d.clientHeight * 2 &amp;&amp; tAP.rF) {
                tAP.rF = false;
                p++;
                sendRequest(addNextPage, "", "GET", "http://" + tAP.LN + "/page/" + p, true);
            }
            setTimeout(arguments.callee, 200);
        };

        function $(id) {
            return document.getElementById(id)
        };
    },
    switchAutoPage: function () {
        this.rF = !this.rF;
        var aE = document.getElementsByTagName('*');
        for (var i = 0, l = aE.length; i &lt; l; i++) {
            if (aE[i].className == "tAP_switch") {
                aE[i].firstChild.nodeValue = this.rF ? "AutoPage[OFF]" : "AutoPage[ON]";
            }
        }
    }
};
window.addEventListener ? window.addEventListener('load', tumblrAutoPager.init, false) : window.attachEvent ? window.attachEvent("onload", tumblrAutoPager.init) : window.onload = tumblrAutoPager.init;
</code></pre>
