Channel 1 and 6 may not be the same on all radios, AND he may not have a computer radio capable of that type of mixing. It sounds like he's thinking about the Hellcat for his second plane, so let's keep it simple. KISS!

Connect the aileron servos to the RX with a "Y" harness. The serovs, arms, and linkage should be mirror images of each other. That is, the servo arms should both be to the outside or to the inside. Not on the same side of the servos, but opposite. This will give the opposite aileron movement you need.

Dr.1