Programs that magically automate the conversion of models from (something) into NWN are probably going to produce output which still requires quite a bit of cleaning and preparation in order to run efficiently in the game.
Having said that...
SomeYahoo wrote...
I have run into a bit of an obstacle.
The placeables for Dungeon Siege's expansion, Legends of Aranna, do not load properly in SiegeNWN.
The game uses files called .dsres, the program is built to only use two of these (Objects.dsres and Terrain.dsres) unfortunately LoA adds another file called Expansion.dsres which doesn't seem to be fully supported.
I was able to get it to load somewhat by renaming it to Objects.dsres but almost all of the placeables get a "cannot load/find texture" error. Half the time it won't preview anymore after the first you click on. Sometimes it will load the texture after a few clicks but the texture is usually without it's UV mapping.
I'd say if you want to continue with the expansion placeables, you should see if Gas Powered Games released a GMax plugin so you can import the game objects into GMax. From there, you could manually clean the objects and export them to NWN. If you don't know GMax, the learning curve on this could be prohibitive to just do this one thing.
Other than this I have practically all of the original game placeables converted (600+), there was several which where rotated/elevated incorrectly and had to be omitted, not sure what to do about those.
Again, using GMax you can make any kind of corrections you need to. This is a pretty common issue with converting models from other games.
And there's also many which have multiple textures but the program only loads 1 (Example: Cat/Bast statues which come in Stone/Silver/Shiny Onyx/Gold but the program only shows the Stone texture), don't know how to make versions that use each seperate texture.
With files such as these, using GMax/NWMax (and probably VelsTools, I forget which one has the utility), you can break the meshes apart based on texture so you wind up with a number of individual meshes which each only have one texture. Again, not trivial if you don't already use GMax because there are some other things you do after that "breaking" process to clean things back up again.