If you have a computer radio then use a mix and put it on a switch.

BUT if you don't then use the Y lead. I taught soemone who had only one working arm to fly and although he had a three axis stick he found reacting to takeoff wobbles a problem with the know on the end of the stick. As his tranny was non computer I set up a Y lead to link rudder to aileron. CHECK VERY CAREFULLY THAT BOTH GIVE THE SAME TURN INPUT. I.E. BOTH GO LEFT. Set the rudder linkage to give a small amount of rudder and the nosewheel steer to normal.

As an aside my ex pupil with one working arm is currently building a 4 engined B 17 from scratch. Anyone want to try one handed fuselage planking?