I have successfully used MIDI control to trigger scenes and faders. I am under the impression that you are limited to the 88 keys, but I have not tried setting up triggering on more than one MIDI channel. I will check it out and get back to you. And I'm sure someone will correct me if I'm wrong, but I think you can only use Note messages to trigger the scenes.
-Adam
www.thesolutionmusic.com