I am planning to do the same thing as N2LRB, I'm wondering if N2LRB has had any luck making the cable and if there are any other options. I will make the cable if I have to, but if there is a commercial variant, I'd look at that as well. Thanks in advance.
Dave, It was easier than I thought to do it. I already had some RCA cables (with a male ends). So I cut the RCA double male cable in half and soldered the center wire of the RCA to pin 3 (PTT) and the shield (wire mesh) to pin 1. I said a prayer and low and behold it worked!