First make sure you have a texture applied to the model in ac3d otherwise it will appear untextured in fpsc
You have to export the model as a .x (direct x) file
Can be found in File/export/directx)
Then you can use a program like entity workshop (even though it's for x9) to make it into an fpsc x9 entity (I'm pretty sure static x9 entitys work in x10)
I think you can then find the model in C:\program files\the game creators\fps creator\files\entitybank\entity workshop\
I hope this helps, I've only used fpsc x10 a few times
Poloflece