Single flight mode where ailerons move up together, and down together?

Is there a way on the Jeti DS-24 to reverse only one side of the ailerons in a single flight mode (not by reverse in servo setup which affects all flight modes)? When that flight mode is activated, I would like to have the aileron behaviour is deliberately modified so that:

Stick left, BOTH ailerons move UPWARD proportionally from 0 to 100% travel.
Stick right, BOTH ailerons move DOWNWARD proportionally from 0 to 100% travel.

A mode like this is useful for endpoint and servo matching during calibration and I want to be able to use it should I ever need to recheck calibration.

I thought maybe I could do it with an Aileron->Aileron mix, or the Butterfly/Flaps settings but so far after 3 hours I have nothing working so hoping someone can help me!

Thanks.

If only JETI would provide a user friendly servo calibration option (like the Multiplex one for example) this would not be an issue.
The current servo setup with the servo balancer is really a a very poor excuse for a simple servo calibration function. JETI leads the pack in many are areas but this is not one of them. It is quite disa[ppointing.

If I want to do it correctly, I assign a 3-point switch temporarily to the aileron and measure the deflections with an angle gauge.

Regards, Walter