Modify Pixhawk MissionPlanner Kongifuration

Need someone to modify the pixhawk to control a quadcopter with tiltable rotors. The Quadcopter should fly forward and backwards by tilting the rotors(using analog Servos) in the same direction and turning around by tilting them in opposite directions. In my opinion it is possible to combine two servos into one channel. So the pixhawk uses 6 Channels to control the entire drone. But also would like to change the configuration to use all servos separately, so all 8 Channels are needed. It is important, that all pix hawk-modes like RTL (Return to launch), autonomous flight etc. are working after the modification. After that you need me to show what you changed in a little how to. Happy to hear your offers ;)