I’ve found it possible to do so by just adding the arguements @vdevice(number of device) to the grab objects you use (you have to fiddle with the numbers to find the right one. I’m not sure about the syncronization issue.
I use 4 dv cams with my project.
Bigger the resolution bigger is sync problem.
Pc have no problem recognizeing multi cams if you have multi firewire cards installed .
With MACPRO i had more problems because apple dvcodec does not support multi cams.(BUT you can try) On the same machine with bootcamp XP runs superb.
Use multiply jit.dx/qt.grabe with @vdevice argument.