Unfortunately the MIDI Solutions part you linked to needs power over MIDI, which as mentioned, is not usually supported by the H9. You can modify the H9 for this, but it involves soldering.
I personally wish that we had given the H9 separate switch and pedal jacks, but I guess there was no space. As a result, if you don't use MIDI, you are limited to either 3 switches, or one pedal and one switch.
