ArduPlane SITL: Actuate Flaps directly in Xplane

I’m working on the implementation of a control-concept for ArduPlane, which also includes actuating the Flaps. Can somebody help me on adapt the SITL, so I can send Flap-Command additionally to Aileron, Elev, Thrust and Rudder? I’m already experienced with sending/receiving Data on Xplane but not yet on ArduPlane-SITL. Seems that the option with MavProxy should be the best option for my case according to

Unfortunately I’m still missing information. I’m very greatful for any advice/link/shared experience. Thank you!