I hunted for this before, so either it's new, or it's so simple everyone else already worked it out but didn't feel the need to tell anyone.

It's based on the "6 modes from two switched using only one channel" concept, but modified to use the D/R switches (or the MIX switch) to give you a switchable output on the elevator and aileron channels, since we don't need them for basic control.

Elevator - gives you +/- full scale deflection of the elevator channel using the MIX switch:

Configure Mix#1

ELE>ELE

Rate: -100%

           0%

Offset -100%

Trim: Inh

Sw: Mix0

Configure Mix#2

ELE>ELE

Rate: 0%

          -100%

Offset 100%

Trim: Inh

Sw: Mix1

Aileron - gives you almost +/- full scale deflection using the F MODE switch.

Main screen: Full left aileron trim

Configure Sub-Trim Aileron: 125L

AIL>AIL

Rate: -125%

           0%

Offset -100%

Trim: Act

Sw: FM1

If you need the aileron channel to go full scale in one direction, you will lose the other end's travel, but you can get it to give you 0 to full + or 0 to full -.

The next step is modifying the code to let you program the aileron and elevator channels the same way as the AUX channels, but as it stands, you could run the ELE and AIL channels direct from your receiver.