ORIGINAL: carrellh
If it's the 5X, you can do it. It is in the manual. One aileron uses channel 1 and the other uses channel 5. Your Y harness will be needed to connect the power supply to the 555 receiver; doesn't matter which slot. You enable flaperons in the ACRO menu.
Why is it that you would have to plug the power supply into the Y harness? would it not just stay in its dedicated slot (Channel 3)?