I'm not sure what sound card you are using, but assuming you know which channels have what data coming from them (a big assumption! ) Then you can use the pins going in to correspond to the pins coming out. Meaning, if you use pins (labeled) 1, 2, 3, 4, 5, 6 as X, Y, R, G, B, (other). then look at this first:
It will make more sense. If you have any questions after that please ask.
BTW, my long time friend, Dean C. Hammonds, designed the op-amp circuit for me and my work with LaserBoy, starting in 04 and fine tuned in 05. It is called The LaserBoy Correction Amp. I laid out the design, did the foil routing and drlava did the CAD drawing that made it into a printed circuit board.