If you have the ability to mix your channels, follow the instructions for your transmitter for Flaperons or dual aileron servos. It makes tuning the ailerons a lot eaiser as you can do almost all of it from the transmitter. This is a transmitter issue, not a receiver one. To the receiver all channels are equal. What you need to do is match your servo channels to the transmitter you are using.

I use a Futaba 9C super and I use Channel 1 for right aileron and Channel 7 for the left one. I could use 1 and 5 also.