Hi,

Claroline from (I assume) http://www.claroline.net/ uses the Tiny MCE editor. I've no direct experience of writing plugins for this, but it doesn't look too complex. Perhaps you can look at some of the example plugins on http://tinymce.moxiecode.com/ and adapt them.

I am planning to write a plugin for this (if nobody else does), but I won't have the time to do this for a few weeks. Hope this helps.