Pixhawk to ESC that control wheels

Does anyone know the dipset switches on a sabertooth 2x12 and into what channels I would plug in a pwm to ppm converter into my spektrum AR610 (transceiver) with 6 channnels and also into what ports I would plug in the ppm converter (that is already connected to the Spektrum AR610) into a pixhawk (to control the rover movement using missionplanner and GPS)? Also I want to keep the ability to manually take over the rover through my transmitter Spektrum AR610 and have the ability to switch this autonomy on and off through a switch on the transmitter. Thank you for the help.