Despite having no NWMax knowledge, I did manage to crank out some robes for other races from human models using that tool.
I wrote this cryptic note to myself:
NWN Armory does not copy robes. There is a tool in NWMax. Use NWMax MDL Loading tool, browse, Import.
Save as .gmax (File > Save on main GMax screeen).
Then under Robes/Armor/Skin, Armour Maker. Select the ini drop down for robes.
This makes gmax files in c:/. Open them in GMax. Select the big blue square (Aurora Base).
Look for "rainbow tool" icon on RHS. This opens the export tool.