Or, if using the serial cable pins and MIC pins are not an option - I remember someone on this board was taking orders for additional sled plugs. It might be overkill - but you could install a 2nd sled connector in the empeg, and modify the plug in the sled.

I wonder if you can get smaller plugs that work in the same manner as the existing sled plug, but have less pins.

I too was thinking of sacrificing the 2 mic pins for my digital out in the car.