Ckeditor Wordcount plugin - How to target specific textareas
I figured it out, hope this helps anyone else out there.

I added the following to my Adminimal Sub theme to add a class to the summary textarea:

function adminimal_sub_form_alter(&amp;$form, &amp;$form_state, $form_id) { 
 if (isset($form['#node']) &amp;&amp; $form['#node']-&gt;type == 'article') {
 // Add class to body textarea for various content types. This is used for the Ckeditor wordcount plugin to target summary textarea. 
   $form['body']['und']['0']['summary']['#attributes']['class']['0'] = 'article-summary';
 }
}


Then downloaded the Ckeditor 4 Wordcount plugin and saved it in the plugins directory (sites/all/libraries/ckeditor/plugins).

In the Drupal UI I went to configuration > CKEditor Filtered HTML (edit) and in the Custom Javascript configuration under Advanced options I added a path to my ckeditor.config.js (config.customConfig = '/sites/all/themes/global/js/ckeditor.config.js';).

This is my ckeditor.config.js:

CKEDITOR.editorConfig = function(config) {

 if (this.element.hasClass('article-summary')) {
 config.wordcount = {
    showCharCount: true,
    maxCharCount: 170
    }
}
// Make CKEditor's edit area as high as the textarea would be.
 if (this.element.$.rows &gt; 0) {
    config.height = this.element.$.rows * 20 + 'px';
 }
}


Here I can set the maxwordcount and loads more besides, but for this project only needed the maxwordcount. This way if the Drupal Ckeditor module gets updated this file will not be affected.