MAX used to talk directly to serial ports and probably still does on the PC version. Although I am not sure since most of my MAX plus hardware days were before OS X and a lot of objects that adressed hardware directly were then abandoned. My thought of using MAX had more to do with using it to generate 14bit MIDI messages out of OSC data since the only high resolution controller for iPad seems to be TouchOSC.

I don't need the Harmonizer screen to show up on the iPad since I will use them next to each other. I more just want to use the iPad as a physical controller. So far I can control the on screen parameters and the 8 external controllers and two triggers via a single screen on the iPad. 

Thanks for that link! MIDI Touch supports Sysex so it looks like I can put all those buttons on the iPad as well.