feedrate override using rotary momentary switch?

[JAZZCNC]

I am also interested how a pot will do the feed override. The CSMIO IP has this function in their plugin but as I understand from their manual, you have to decide whether to use the mach3 feedrate or the manual pot. I cannot imagine a way to do the override (+/- of the mach3 feed value) with a pot.

Yes that's correct and it's easy. The analog connector provides 10V for the pot and you feed it back into the analog input. The control then overrides feedrate or Spindle speed based on the returning voltage.