I'm helping a friend locate these audio breakout cables. If you have a set you're willing to part with please let me know. They originally were packaged with a Simplifi Digital amp (out of business now?)
I think this cable type also came with some Soundblaster cards a few years ago. I think you can substitute some 3.5 mini's with RCAs on the other end and make this work. I think you need at least one from a camcorder setup but not sure. I recall using extensions for this setup from Radio Shack but I think Parts Express might also have them.