ORIGINAL: joeflyer
I don't have a 12X but have done similar things with my 9303. If you do it as Craig suggests I don't think your trims would work properly. Try leaving it set up as you have and just mix aileron to elevator. You might need to use two mix functions, one for each elevator half. You could also use a mix switch to turn the feature on and off if you wish.
You'll have to play with it a bit. Good luck.
Joe
With the setup I described, the trims will work properly if the "+" option is selected for each mix. However, as Joe suggested, it
might be possible to mix the ailerons directly to the elevators. Obviously the elevators have to be on separate channels and depending upon how you set that up (using MATE or through a mix) the direct mixing may or may not work correctly.
Once again, you just need to play with it. If it was me, I would copy your original program to a second model and be able to try different things without loosing your current program.
Craig