Textarea custom button shown for certain pages/weblogs in backend

Hi guys, we have have created a ‘notepad’ application for our site, which allows users to make a note of the content on the frontpage for a certain section of the site. In the backend we are using TinyMCE for our WYSIWYG editor, we have created the custon plugin for this & the extra button is shown on the Textarea WYSIWYG.

So when adding content for the new publish page the extra ‘notepad button’ (TinyMCE WYSIWYG) is available, but as I’ve stated above this is only for certain section of the site. So we need to be able to disable/not show the ‘notepad button’ for either: 1) Certain user/usergroups or 2) Certain weblogs or 3) Create a new Field Type (eg, textarea2) as there are currently only 5 available: http://expressionengine.com/docs/cp/admin/weblog_administration/custom_fields_edit.html

Remember this is only for the backend of EE, not the frontend.

Many thanks