The Midi foot controllers around are mostly generic and can be used with 99% of the midi-capable devices you have around.... in other words, most of the available choices in the market would make this possible for you.
Looking at how compact your unit is, probably a small controller that offers you program changes (up.down) like Rocktron's Midi Mate would do the trick. If you want to jump through the patches you may need something that helps you navigate better, perhaps a Behringer FCB1010, but is bulky, big and difficult to program manually. I would go with an FCB if you have other midi-capable devices you want to change at the same time, then it would be justified.
I use the Logidy UMI3, which is USB, and is small, simple, rugged, perfect. Perhaps you can put a USB to MIDI cable and get this done, and send program changes (Up/Down) directly to the unit.
I hope this helps.