Check out
http://www.uberdroid.com under FPSC addins.
At the bottom there's a rock you can download as an x file that is just right for importing with Magic FPS
http://www.uberdroid.com/fastfps/index.htm (where you can xyz scale and rotate it however you like.
Use the "stones.tga" texture that comes with MFPS (or whatever you want) to texture it.
Save it, change it a little bit, save it again for lots of stone entities.
If you don't have Magic FPS you can still use the x file and include it manually or with some other program. Enjoy!
