Is it possible, or has anyone already, modded the CS?
I would dearly like to add my own 'folders' in the Object Window.
I need a way to organize my additional meshes - I have at least a 1000 extra meshes in there. I would like to add Static II and Static III etc.,

In theory, someone could write a patch to modify the executable, similar to how the Morrowind code patch changes the Morrowind executable. I'm not sure how much you could change (your request would necessitate the addition of new menu options, for instance), and it'd very likely take a lot of time and dedication to complete.

Seeing the http://www.tesnexus.com/downloads/file.php?id=36370 for Oblivion CS, one would think that something similar should be possible for Morrowind as well. But apparently nobody cared enough yet.

There has been some work on scripting editor integration (http://www.gamesas.com/topic/1210591-morrowind-script-checker/page__hl__mwsc), but it seems discontinued.