Actually, it's getting kinda late here almost midnight and I got skool tomorrow, so here's a .uti tutorial, I am almost positive that this is what you want.
Okay, so you want to make a mask eh? Well, it just so happens that I did this a little while back *about 3 months* so, I think I can help you with this. Basically, it is the same as if you were doing anything else. I personally, always open up a mask.mdl just to see the rough size it should be, then I make the .uti and change resrefs and stuff... anyway here's a tutorial.
Things you'll need:
1. KotOR Tool
2. A mask (Already created preferred)
5. (Optional) a brain :-p
Okay, so first start off by opening up your KotOR Tool and select a mask. (In my case i_mask_001) Then you will want to get the .MDL's and .MDX's exported to the same directory. In KotOR 1 you will click Aurora Model and Aurora Model extension to bring up from there export your mask.mdl and .mdx. Now, open MDLOps and select your version of KotOR. Then click select file and click "Read and Write model." *NOTE: MDLops will automatically change the name of the mdl to -ascii in order to ensure you do not overwrite it and to show that it is no longer a binary file.*
Then go into NWMAX and go to MDL Loading. Click browse, then select the .mdl. After this check "Import Geom Only" then import. Then go to file>merge>(Your created mask) *NOTE: MAsk may need to be exported to .3ds* Now, depending on how large the mask is, you may need to scale it down so that it may be around the same size as the .mdl you imported earlier. It's always a good idea to match the to ends together, depending on your mask, this may not be necessary.Then select the .mdl and click the edit tab. From there click the "editable poly" menu and choose select by element (The cube) then select attach and select your mesh. Now, delete the mask (NOT YOUR MASK). Now select the AuroraBase (Green Square), uncheck Do Sanity Checks, choose an Export Directory (Choose a different directory for this to ensure you do not overwrite the original .mdl) , then click Export Geom only.
Now, go back to MDLOps and select the new .mdl and click "Read and Write model." When it's finished it will say Finished Processing Model *Depending on how many faces your model has this may take a little while*
Now, open up KTOOL. Then open BIF's and select *For KotOR 1 at least* templates.bif then blueprint, Item. Then find a mask (KotOR 1 g_i_mask01 is the one I will use.) and double click it. Change the template resref to the name of your model dropping the .mdl extension of course, same goes for the tag. Keep everything else the same. Then you can go through the rest of the tabs at the top and decide what you want them to be. then save that file to the same place you used mdlops to read and write your models. (This makes everything a little more organized.) Now, drop the files into your override folder and you should be ready to go.
The finished result should look like this.
Here it is ingame (BTW: I just used a box as the mask and the texture carried over with the mask.)
BTW: If you want me to go through changing the icon and texture just let me know,