spaceanimal, there is a reaper plugin called ReaControlMIDI. You can use this to control CC values the same way as you would a standard FX parameter, through modulation or via timeline envelope. It looks like this: The JS plugin mentioned previously would be great if you wanna place the CC values within the MIDI editor though, which does actually give you more editing flexibility if needed. Try both, use the one that works best for you, and let us know if you have any issue :)