Guide on adding a new model, animation, and creature to HoMMV

Good afternoon, please answer a silly question.
I want to manipulate the models of 5 heroes in 3ds max, but I can't figure out how to load them.
There seems to be a program called Arkhangel for this, but I can't understand where the models are; in data.pak, there are only .xdb and .dds files, and none of them can be opened by the program.