Interesting - and very complicated. But using your instructions and a little creativity, I am able to do what I wanted.

Recognizing that I could not get -100 to 100 without first stopping at 0, I set up two mixes, one for the air brakes and one for the tail hook. Both are attached to switch SE, with mix 1 (Aux 4) set to Off/On/On, and mix 2 (Aux 3) set to Off/Off/On. With that I set up the function for mix 1 as -100 to +100, which creates a "V" curve in the Prog. Mix window. Now, when the switch is OFF, the servo is positioned at +116, and goes to 0 when the switch is ON, in either ON position.

For Mix 2, I set the function to 0 to +100. I then set the end point for the channel to 0 on the left and 140 on the right. This creates a linear curve starting at the mid point and to-140.

This gives me 1/2 servo travel for each function, but with clever mechanical set up, (longer arms, for instance) I can reach the full movement for the controls and have the switch setup I wanted.

Having been a software developer for 25 years, I wonder why Futaba decided to add these restrictions into their operating system, but whatever. This is an overly complicated way to do something, but it is at least possible.

Thanks for the tips.