He encontrado esto pero no tengo ni idea de ingles..
Nev uses chaining. It means, that he doesn't switch drum racks like people would normally do, but he changes them in a really complicated way so that it is almost impossible to put into words.
But personally I would recommend you to just change drum racks. To do that:
First, create as much drum racks as you need (be sure to give each of them a name)
Second, make LED feedback tracks that corresponds to all of them (for example: 3 drum racks and 3 LED feedback tracks)
Third, to switch between drum racks, press MIDI button in the upper right corner of Ableton. It should turn the entire screen blue-ish. Next, click on drum racks arm recording buttons and then press on one of the round buttons on your launchpad. Do this only for drum racks, not LED tracks.
Fourth, on LED tracks, bring up the MIDI I/O (A small button in the center right). And then a little options window should appear under each track. There you will see "MIDI from" and "MIDI out". Click on "MIDI from" and select your first drum rack. Do this with every drum rack with a different LED feedback track.
That should be it...