Rover with single quadrature encoder

I modified a Traxxas monster truck to work with Pixhawk and 2(blended) GPS units. Auto Mode and programming works well. I am now attempting to enhance the slow speed operation by adding a single quadrature encoder to the motor. The encoder is connected to WENC(not 2) and I am able to read the distance value and it appears to be calibrated properly per distance. Following process in Wiki. In order to use a single encoder for slow speed mode, should the encoder be connected to WENC or WENC2 or both? Any other special settings to tell the Pixhawk that it should use standard steering and not slip steering?