"ReaControlMidi" http://audio.tutsplus.com/articles/general/how-to-use-reacontrolmidi-tuts-premium/ Here is a tutorial on the "ReaControlMidi" plugin: http://audio.tutsplus.com/articles/general/how-to-use-reacontrolmidi-tuts-premium/ It's should be installed in your "Reaper" installation, in the "Cockos" plugin folder...