There are two ways.
You can use an Aux Switch defined as “Performance Switch” with algos that support it, or attach a momentary switch to you Expression Pedal leads for ‘instant expression’ for algos that don’t.
I’d use the first, and I’d use PitchFuzz
On my patch above you just have to assign the alternative voicing to the ‘Hotswitch’ instead of the expression pedal.
