Xilch,
Greetings. Not a tough problem to fix.
Once you have a terrain that you like, export it as an .x, and place it in ...EntityBankfolder of your choice.
You must create (cannibalize) an .fpe file, so that FPSC knows what the heck it is. Place it in with your .x file.
SIZE and ROTATION can be directly altered from within the .fpe file. Be sure to place the terrain just below the working surface of your level. Manipulate the HEIGHT in the .fpe to adjust this.
Play around with entity's properties and you can make the weight too heavy to move, and make it invulnerable. Making it STATIC should work too. Texture must be pointed to in the .fpe file, and must be a single map.
I hope this helps and gets you off to a good start in getting your terrain working.
Thanks,
Seth Black
"...I'm sorry, could you repeat your question a little louder? I'm a trifle deaf in this ear."
- Willie Wonka