I will get Gigastudio 3 at some point, but currently am still using GS v2,5xx.

With my version you must open Giga and then open your designated audio/sequencing software from Giga.

I'm not sure what to do with PT, but with Sonar and Samplitude it is very basic. Once you have MIDI data down in your sequencer, you can manipulate various controllers just as you would any other MIDI data and GigaStudio will play it for you.

dude sell your protools hd and run everything in cakewalk with a pc. just kidding if you have an open adat on your hd rig you could get an interface for your pc that has an adat out and send the appropriate outs to the appropriate ins. I would prob map all the midi stuff in pt first and use that to control the gigastudio i would think this would give you the most accurate sync. another option I have seen progs that let you run rewire from a remote comp. As far as something that would work cross platform for what your doing i don't know but that would be cool huh. just network the 2 comps together. but i would think the first suggestion would be a more stable reasonable solution.