I'd love to be able to control parameters within GR7 via my MIDI expression pedal. But unfortunately, MIDI control is available only in the stand-alone app. I contacted NI support (opened a ticket) to ask if there's any planned timeframe to add it, and got this response:
MIDI control in Guitar Rig 7 plug-in is something that may be available in a future update but I do not know the timeframe for implementation. I will be sure to forward this to the development team so they know the demand!
Best regards, Jonathan
If others would like to have MIDI capability w/in the plug-in, please let NI know! If enough folks ask for it, perhaps it'll move up in the feature priority queue...