Make locator.updatedb run daily on Snow Leopard w/o hacking /System/Library?
The way I understand it, that System folder launchd job does nothing but execute /usr/libexec/locate.updatedb itself.

So simply create your own launchd job executing /usr/libexec/locate.updatedb that runs once a day.

As a sidenote, here's a Super User answer which recommends using mdfind -name &lt;filename&gt; instead of locate so that you can use the Spotlight database which is continually updated.

And this Ask Different answer has more info on creating launchd jobs if you need more help with that.