In most cases the BEC is set at around 5 volts and a limited amount of current. If you plug a 6v pack into the battery slot it will drop it down to 5v or what ever. BEC's are most commonly found in AM receivers and ESC's.

To eliminate the BEC,(if no switch is found) wire the battery to the switch then to a "Y" harness that splits to the receiver(steering channel) and steering servo from the switch. Your high torque servo will gain most performance with a "Y" harness as it will receive maximum voltage and current.

I would actually recommend using the "Y" harness anyway. This will avoid drawing to much current through the receiver, full potential of the servo will be achieved, ect.

Ryan