Invert output with switch?

I'm guessing the solution will be with virtual channels and a complex mixer, but can't nut it out!

I have a car setup I'm experimenting with, with dual-rates set up (devo 6s) on FMod for 60% and 25% throttle output of the following 9-point curve;
-100, 0, 0, 0, 20, 40, 60, 80, 100
Idea is to have a small window of "reverse" down the bottom of the stick primarily for quick brake jabs, then a definite dead range, then a smooth curve from a little below mid-stick. Dual rates are for potentially handing it to my 4yo son so he can't get into too much trouble.

Thing is I'd like to be able to invert all of the above, including the dual-rates, at the flick of a switch, eg. Mix. Reason being, while the ESC is setup to do a quick brake burst when you hit reverse, it's a real pain to attempt to actually get it to go in reverse with a standard stick input; you have to go back up to zero, wait a second, then reverse again, but it's hard to get the stick positioning right without resetting the sequence. So I'd like to be able to chuck the stick into the dead range, flick the switch, and have the inverted input range available for better definition of reverse throttle input (and to definitely be reversing).

One of the problems of not having a centering spring, but worth it if I can get the above working I reckon.

Yes, and it's quite simple to do:

1. Go to the mixer for THR that you have been working on (with Dual rates) and highlight "Expo&DR" and press R+ to change it to "Complex". You will now have 3 mixers doing exactly the same as you had before.
2. You will need to add 1 mixer to perform the reverse, so increase Mixers by 1.
3. Change Page to the same number as Mixers to edit the last mixer (the one added).
4. Set Switch to the switch you want to use for reverse.
5. Set Mux type to Multiply.
6. Leave Src as it will not be used.
7. Change Curve type to fixed.
8. Change Scale to -100.
9. Leave Offset at 0.
10. And finally select Save to save changes.

Brilliant, thanks for that Indigo, implemented and will see how it goes in the real world on the weekend, see if the end result is as usable as I intended.
I set up two additional mixers, both as per above, for Mix1 and Mix2, so I can just throw the switch and not matter which lower position it ends up in. Sometimes I miss the simplicity of the two-position switches of the 7E, eg. for heli throttle-hold. Gear and DR aren't conveniently placed for quick throws, and I've got gear set up as the safety in this particular case anyway (when carrying etc., not for emergency shutoffs)

PS. Ah, a fellow Brisvegan!