I extracted the proper ResType names out of swkotor.exe and wrote a little utility to stuff all of the files in the current directory into a RIM file. Binaries for these utilities are here
and there's also some source code
if you feel like wading through some very rushed and ugly C++ (you'll need MinGW and Jam/MR if you want to build it as-is, though it should be fairly easy to build with other toolchains).
Someone ought to add the new ResTypes to NWN Explorer to get it to stop giving numeric extensions for resource types it doesn't understand.
I've been looking at the area formats a little bit, and it makes me want to go hide in a corner somewhere. =/