Here’s how I do it for the Diatonic & QuadraVox algorithms.

https://www.eventideaudio.com/forums/topic/pitchfactor-key-toggling-over-midi/#post-123733

I built this chart for use with any kind of MIDI controller (and originally, a PitchFactor), but the FCB-1010  is particularly geared for this in a live application.

It can send two CCs at once, for KEY + SCALE changes with one switch.  10 switches per Bank provide easy access to a lot of combinations.

Notice there is a small range of CC values for any given KEY or SCALE.  Select your CC message, and any one of the individual CC values in each range will work.