I’m not entirely sure I understand the request. Can you be more specific or provide an example? For instance, are you trying to switch between a reverb preset and a delay preset? With more information, I’m sure we can get you an answer. Welcome aboard.
You can just save two presets if you like and the right button on the H9 (with the label "Tap" above it) cycles you through the presets. Hit active on the first preset (left button) then hit the right button to advance to the next preset. The new preset flashes but isn't active until you hit the active switch again. Now you're using the second preset. None of this requires the use of an aux switch. Does that answer your question?