Do you mean Script Extender, also known as MWSE?
If yes, then you do not need to edit anything. Just fire up the Morrowind Launcher, click Data Files, check a box next to a mod name. Then exit the launcher and un the game by double clicking on MWSE Launcher.exe
Yeah I meant extender. Maybe that's why I didn't get the results I wanted in Google...
Where is the MWSE Launcher? I only see MWSE.exe, and that launches the script editor thing. I have MWSE 1.2. if that makes any difference.
EDIT: WOW, I'm stupid. Idownloaded the Morrowind Script Editor instead. Uh, what does the Morrowind Script Editor do then?