POSCTRL and collective pitch

I have a twin rotor helicopter configuration (V22 Osprey) that I have working with a custom mixer in MANUAL mode. I was about the try POSCTRL with the GPS when I got to thinking about altitude control and the pixhawk 2.1. My throttle is in governor mode with the ESC so changing throttle values does nothing to altitude control. Collective pitch is controlling the altitude. Therefore, should I just pass the raw RC throttle value for throttle to the PWM output and use the throttle from group 0 to control pitch? Will that allow POSCTRL to work correctly assuming I have the pitch curve set to hover at half stick? Not sure what the best method is here so any suggestions would be appreciated.