ok, let's see:
For props and static models:
a) download "Deep Exploration" (google it):
b) from Maya, activate teh .obj plugin and export the model
c) then from "Deep Exploration" transform the .obj model into the .x to be used in fpsc
For humanoid models (npcs) and weapons (weapons for the 1ยบ person):
a) download 3ds max trial
b) from Maya, activate the .obj plugin and export the model
c) from 3ds max load the model, rig it, animate and finaly export it with the .x plugin found in this site
Why this 2 ways:
It seems that "Deep Exploration" is able to transform and modify all models that will look static in fpsc.
But it can't manipulate the rigs of the models, including the animations (i have the last version of "Deep Exploration" and it always crashs fpsc when the humanoid/weapon is loaded in fpsc.
Hope this helps
(There might be a .x plugin for Maya, but i can't find any, but in fact, i really never searched that much to say if there isn't any).
Anything else, jsut ask.
My love is seperated in 2 parts, 1 of them is 3ds Max 7, the other; FPSC.