Hey Keith,
sorry, been away for a while and don't have my diagrams with me. I do know that you do not need to hook up the speedo output from the cpu. I originally tried that but it will not drive the CableX. Use the vss out from the trans (and T-splice into it so it still goes to the CPU so it will make your speed limiter and reverse lockout work properly) to go to the CableX box +.
Good luck,
Mike