For those that are following along and care...
Rumor has it the pin out wiring assignments for the stereo 1/8" minijack RECEIVER IN port on the Xantech units is:
Wire Stereo Miniplug
--------- -----------------
IR SIGNAL TIP
GROUND CENTER COLLAR
12V+ SLEEVE SHIELD
I HAVE NOT CONFIRMED THIS THOUGH. Use this information at your own risk. It was obtained through a third party, NOT directly from Xantech.
{ETA - UPDATE. I have confirmed the pinouts, and they are as indicated above. I confirmed them on a Xantech installation document}
E.