I've tried to edit Visas's head mesh to add some hair on to her using nwngmax. I've exported the aurorabase thing in nwngmax but it's exported it as 'P_VisasH.mdl.ascii' not as a .mdl file. I don't know if it's supposed to be exported as a .ascii file but for some reason for me it is.
I've also downloaded a 'NwnMdlComp' program to try and turn it from a .ascii file into a .mdl file.
Neverwinter Nights and KOTOR does not use identical model formats so the NWN model compiler shouldn't work to use with KOTOR models.
You'll either have to use MdlOps (
http://www.starwarsknights.com/tools.php#skmo) or in this case Taina's Replacer Tool (
http://ds1.pcgamemods.com/core/11335/Replacerv10.zip) (since MdlOps currently can't handle modified head models fully) to convert the ASCII file with your changed to the MDL/MDX files KOTOR uses. See the modeling tutorial forum (
http://www.lucasforums.com/forumdisplay.php?f=595) at the top of Holowan for some information on how this works, and make sure to read the ReadMe files that come with the tools since they contain tutorials for how you should use them.