Got the wiring squared. Large wire going from driver battery to the converter (12/24v). Power goes from there to the ESC module, the assist adjustment knob (potentiometer) and then to the steering shaft assist motor. It seems power is also supplies from the converter/step-down to the 12v stereo. I haven't chased the wiring to the hitch (7pin) back yet or read things out with the meter yet but more to follow...
Converter? You indeed found more nuggets. That's an optional module worth about $250, which just made it into production last month. With a standard 24V set up, the EPS setup draws current from one of the two batteries in a 24V car. The converter load balances the current from both of the batteries, thus ensuring equal battery life.