1) In the Global Mode, go to (6.1-1) [Menu]->[Ctrl]->[Foot].
2) Set Foot Switch Assign to “Foot Sw CC #82”.
3) (6.1-3) [KARM2] -> Scene -> Set to CC #82.
4) Plug an additional footswitch into the back jack labeled “Foot Switch”.
☞ Parameter Guide, Pages 145-146.
You can now change Scenes with the Footswitch - if it is a toggle type
footswitch, it will change back and forth each time you press it. If it is a
damper pedal type footswitch, it will change Scenes as long as you hold it
down.
Doing it this way, you can still have a regular damper pedal plugged in to
damper, and get both effects. Or you could skip step 1 and 2, and just
set step 3 to CC #64 and use the damper to change scenes, but this
might interfere with normal damper settings.