I have started to put together notes on the format of the models in the full version of Grim Fandango. It has some holes however and any suggestions would be welcome etc.
I probably won't get a chance to look at this further for a bit anyway.
I have a bit of code that converts things to a text format like Jedi Knight and the grim demo however its not very useful as there are unknown bytes that are variable.
Anyway have a look over here
if this kind of thing interests you.