If you are talking about this one with the building pack:
http://ww2media.thegamecreators.com/
Than no need to fear.
You just have to use a program to get the models into FPSC since they are not FPS Ready. I don't know anything about magicFPS, but there is a free program out there that lets you put any .x models in FPS creator. You can download it here(Make sure you watch the tutorial videos!):
http://www.fpscreator.com/downloads.html
"FPS Creator Entity Maker"
If the textures are not .dds format, we need to do that. Google DDS Converter 2, and download it.
If you are talking about the weapons, then thats another story. Search the forums for a tutorial on how to get your guns into FPSC.
Hope this helps.