Although off the shelf, the EZG+ won't control an e-drive, I have sucessfully made a black box that allows a Cultiva ATC ontrac to operate a Raven steering valve in place of the steering wheel motor.

 All that one would have to do is scope the signal from the ez steer -find out if it's analog or pwm digital- capture it and condition it to operate a steering valve; that's basically all that the box I built does.  A relay and some diodes split the alternating pulse wave into two seperate signals, run them through some buffers and out to the solenoids on the steering valve.

Dan Van Gilst