Crossfader Note allows you to dedicate a MIDI note on a track to control the crossfader. You can choose the default crossfader position (note-off) and where it goes on note-on, as well as the time taken to transition.

Thanks to u/leser1 on Reddit for the idea!
Download the .amxd file from the latest release or clone this repository, and drag the CrossfaderNote.amxd device into a track in Ableton Live.
Note - Sets the MIDI note to trigger the crossfader action.Thru - Controls whether the above note is sent to the MIDI output of the device.Time - The duration that the crossfader action takes.Note Off - The crossfader position for when the note is off.Note On - The crossfader position for when the note is on.