Proton is just wine with some extra stuff added, if you install protontricks this explains what to do.

protontricks-launch --appid <APPID> <EXE>

Should get you what you want, you can find app id by looking at the url of the game in the steam store or using

protontricks -s <GAME NAME> 

You should be able to use those mod installers by running them with wine within the wine prefix Kotor is installed in surely?

Yeah I realised the only games I cant play on linux are the ones that really don’t respect my privacy/time/wallet so it ended up a net benefit