Hey guys, just wanted to thank you for sharing this tip with us. I've been wondering how to do this for a while and never thought that although you could control these parameters through MIDI to build something in the environment to control them. Very cool! Here's a section of a template I built that contains a ready to go mixer with 128 audio, 64 MIDI and some auxes for effects. On screenset 2 at the top of every channel strip is a box to link channels without volume or pan and the floating window contains an "on/off switch" for all 15 insert slots on the audio, MIDI and mix bus tracks. Hope this helps someone else, let me know if there are any questions.
Plugin Bypass.logic.zip
mixer environment with plugin bypass and channel link