I did it in OS 9/X. poser 4 on slave drive, poser 5 on external firewire drive, poser 7 on main drive. it was done by dragging the poser 4 folder to the slave drive from an old OS 9 computer, and dragging the poser 5 folder from the main drive to the external drive. in mac OS, dragging a folder is the same as copying it. they all work o.k., and poser 7 can access the runtimes on the other drives.