I have Nemesis Of Katarn on my file page at Filefront, been there since last April, sorry about that!!
Nemesis Of Katarn
As for the problem with the Mustal mod, I'll look into it and get back to you with the answer.
EDIT: Okay, I found where you found this one at (JK II Classic Files). I read the readme. No wonder you were confused. The person who wrote it didn't double-check what he wrote. Put the folder that was in the .zip file in the GameData folder only
, not in GameData/base. And then click on the .bat file that is inside the folder. If it still refuses to load up, put the .bat file in GameData instead and it should start up (I hope). Let me know if you get it working.