My 2c- 

I think it wouldnt be that hard.. but from a different perspective. 

The agency to do this is some kind of Midi XML map. . . which is editable, I understand.. but not easily right now.

MAYBE.. in the H9 app.. there could be a screen to directly edit the MIDI Map? So you could get to it easily. Like the PC map.

Or.. on a preset-per-preset basis .. you could have an option to “Fire X PC Message”.. default being Nothing.. OR the Default XML Map- but that starts to get confusing. The first way is probably best. An XML Map screen just like the PC Map screen.

What you really need is a MIDI controller. 🙂