I had already ordered and installed the PAC-Audio C2R-CHY4 that I used to control my factory amp, so it just seemed a little easier to me to use their steering wheel control unit as well...no reason that using RT's software and a CAN-USB adapter wouldn't have worked just as well though.
I looked a bit on the canhack.org site, but I didn't see it in the software section either. Maybe just send him a PM and ask him about it. I'd be curious to know as well, however, as I'd like to eventually plug into my CAN-BUS so be sure to share what you find out.
Did you have any volume issues with your build? I'm running my setup from CarPC to PAC CHY4 into the factory amp but even at full volume on the PC the audio is only moderately loud.
I haven't really had too many issues with volume, but I did notice a pretty big difference in volume when trying a USB sound card, instead of the internal sound.
What I settled on is using the internal sound, but I have the audio coming out of my PC and into an electronic crossover and then into a small 4 channel amp in my trunk. So I'm sort of pre-amping the audio before it gets to the CHY4.
Not sure, it does seem to work fine for me though. I have two channels of the amp going to my sub and two channels going to the rear inputs on the CHY4. I do have the output going to the in-cabin speakers turned all the way down I think...mainly just used the amp because it made wiring to the front really easy for me.
I ended up buying a small 10V pre-amp with adjustable gain ( http://www.cacheaudio.com/cloc+d.html ) for $70. It's only just over 3"x2" and absolutely solved the issue. The factory amp is not too bad, on to CAN-USB
So for now I've just got the C2R-CHY4 on the way (by the way this is for a 2010 Jeep Patriot).
You mentioned that "after a few false starts" - by any chance did you examine the outputs in the C2R itself? I mean the part that connects to the SWI-PS adapter you're using - perhaps those might work? Or are the signals not in a usable state at that point?