I think Clark addresses this issue in the TK60. The Asp is set up for Machine gun 1 and 2 and each has it's own fire switch.

I added the turret MG for that tank I just did for a guy at work, and all I did was just as Joe said, tie right in to the existing MG. Works just fine. But remember that with the clark board and turret MG the Taigen airsoft w/mg slip ring kit won't work, you'll have to get the IR slip ring, and that won't be plug and play for airsoft. To get it just right with a clark and a turret MG you need an 8 wire slip ring.