It is in lib/editor/
I don't know how difficult it is to develop for it. If I understand correctly, you want students to be able to press a button which automatically copies the wiki text to Word, they can edit the text in Word, afterwards press another button and the text is entered in the wiki again. Is that right?
Have you looked at Mozex
? This extension for Firefox
makes it possible to use an external editor whenever a textarea shows up. (It doesn't work with HTMLArea so you should disable that in your user profile)
I haven't tried connecting openoffice/word to it, but it worked with vim. I am not sure what happens with all the formatting openoffice applies.