I recently upgraded from my trusty old Turnigy 9X to a shiny new Turnigy 9XR, and had to figure out the channel mixing for it to work with my APM.
There are a few resources on the internet on how to do this (including here on diydrones), but non specifically for the 9XR.
I managed to set my transmitter and APM up such that I have 3 separate switches.
Airframe: Finwing Universeye Penguin
Autopilot: APM 2.5+ with Power module
GPS: 3DR LEA 6
Telemetry: 3DR 915 Mhz
Motor: Finwing stock M2220 1350kv
Propeller: Master Airscrew 3-bladed 9 x 7 Pusher
ESC: Finwing stock 40 A (5V/3A BEC)