Reply to 2 macs, 2 abletons, 1 s4 sync help

So a friend of mine and i have recently started a Dj duo. We're having trouble syncing all of our gear properly. I'm running ableton suite and Traktor s4, he's rockin ableton and a USB controller, his sound out is via USB soundcard as well. I don't even know where to start.

Thanks for any input ahead of time