From the bidule forum:
I have a channel in ableton with 3 sends on it. I would like to be able to turn up a send and at the same time as this the channel volume goes down automaticlly... Is this possible and can someone help?
Doing that is easy, you need to setup something in Bidule to have 1 CC produce another CC with the inverted value and then map each one to the relevant controls in Live.