There is a good tutorial on a way to use AE 3D objects in Particular here:
http://www.graymachine.com/v3/07-particle-orientation-in-trapcode-particula...
When I use 3D particles, I typically create a looping animation and use that in Particular Set the particle to loop with a random start time. Just keep your precomp size pretty small so AE doesn't bog down.
Trent
Trent Armstrong - Creative Cow Leader
http://www.dallasaeug.com