Just in case it might be helpful, I just posted a “tutorial” on how to replicate the functions and behavior of the two buttons on a Chase Bliss Blooper on an MC3 (or any other Morningstar MIDI controller).
It’s here: Using two buttons on an MC3 (or MC6, etc.) to replicate the two buttons on a CB Blooper.
Note: in my post I reference the Morningstar video, “The Shift State - The third, temporary toggle position,” which I believe addresses exactly what you want to do. What I add in my post is getting a second button on the Morningstar to replicate the “Stop” button’s functionality (and how it interacts with the Rec/Play button) as well.