Using MK15 for SITL simulations

We are currently using MK15 transmitters for flying drones. I want to train people using realflight, ardupilot and MK15. Interfacing MK15 to control SITL/realflight will be useful because I wont have to spend on purchasing new transmitters, and we can do away with the learning curve of adapting to new transmitters.
How can I connect the MK15 to realfight/AP/SITL to run simulations?

try using HIL simulation