The PCM is a standard across manufacturers, as the servo pulses are derived directly from the baseband PCM. All you need to do is locate the PCM pulses in your receiver and make a connection to it > pin 8 arduino.
Ed, arnewbie is referring to PCM (Pulse Code Modulation), not PPM (Pulse Position Modulation). PCM is an encoding method where the actual digital values are sent as a serial stream. Unlike PPM it is not standardized and it needs a lot more work to decode.