Having programmed a DVS before, I can tell you that this would require a very large amount of work (in saying that though, getting the basics going probably wouldn't take too long) - and work that would divert attention from the video side of MixEmergency. So, yes, it would be possible (though, with the TTM 57SL not sending MIDI, it would not work for that mixer in particular for video crossfading), but not really an ideal solution at this stage.
