Look into the
FPSC Toolbox. It's what I use for getting my models into FPS Creator, and it works great and saves
a lot of time over doing it manually. I've had it for over a year, and it was definately worth the investment.
Load your own mesh and texture into the program, mark a few boxes to select the entity's material and effects, give in a name, and save. The program automatically creates a thumbnail and .fpe file, and then drops them along with the texture and mesh files into an entity folder ready to use in FPS Creator.
Kravenwolf