basically mask everything out in the photos u want to seperate in PS and have them on seperate layers then import the psd as layers drop them in the comp and turn on 3D switch for all of them and pull them apart in Z space set up a cam and go to town…it gets cool when you start adding other elements like skies, dust flares, etc. thats the quick and dirty version check out chad perkins tutorial on lynda also he shows you how to use displacement maps on the photos that really make the subjects pop