If it has not already been done by another mod you should have those two lines in the appearance.2da file changed so that a 3d model and texture is assigned to all chothing types for it. Otherwise it'd only work if the character with the appearance is naked, and would most likely crash the game if something was equipped in the body/torso equipment slot.
Usually you use KotorTool to modify 2DA files. If you're not interested in learning how, here (
http://www.algonet.se/~stoffe/assassinfix.zip) is a pre-packaged one-click solution I just put together that should work. Unpack the folder in the zip-archive somewhere (not into the override folder though!) and run the patcher exe (Fix Assassin Appearance.exe) inside it. This will modify the appearance.2da file for your KotOR2:TSL game for you, assigning models to all the outfit columns for those two appearances. :)
Forgive my lack of echnical incling, but if I understand this correctly, this will allow me to use an appearance.2da folder in my override, and by changing my character's appearance to one of the sith assasins after installing it, I can wear clothes over it? If so, that would be a great solution to my problem. (Because I have so many good appearance.2da mods, and choosing is a painful task indeed)