I've just been running cajoNES synced and slaved to Ableton Live and also running in sync with my modular and Octatrack! You can drag the tempo around in Live and everything - including the NES - responds as it should.
Admittedly my NES is currently lying on it's top with wires hanging out of the expansion port and it is very early days, and there will be limitations but it works.
The code part is actually very simple. Once I've sussed out a few details I'll definitely be looking at grafting the sync code into Pulsar and PR8. NTRQ is a slightly different prospect because of it's use of the second controller so that will need some thinking about.
I'll post a better explanation and video soon.