I have a Novation Impulse 61 and have been toying with setting it up in AZSlow (right now, just doing some prelim work to see how it behaves using MIDI-OX). I think I've figured out the problem with the mod wheel (it occurs with the expression pedal and sustain pedal too).
I'd exchanged some email with Novation to try to set the pad colors, and get better control of the buttons and lights in general. In some exchanged emails, they sent me the sysex sequence that puts the Impulse into "Control" mode: F0 00 20 29 67 06 01 01 01 F7. Control mode lets you do a few things you can't normally do: you can directly read almost all the buttons. You can toggle the faders between mixer and midi mode, and read different messages off them depending on the mode; same with the rotaries. You can toggle the lights on the mute/solo buttons (but not on the mute/solo mode toggle, as far as I can tell). You can set the colors on the pads (red/green/amber, varying brightnesses, flash) when they're in Clip mode. Lots of possibilities!
It does come with a drawback - setting that mode locks the mod wheel, expression pedal, and sustain pedal to channel 3, which isn't very helpful! I think that's bug, and I've asked Novation if they know a workaround - no word yet.
However, I found a workaround. You can turn control mode back off (losing all its function, and losing any lighting you did) by sending F0 00 20 29 67 06 00 00 00 F7. (I'll just abbreviate from hereon out - incidentally the 07 19 function referenced earlier in the thread doesn't seem to do anything, and the Impulse doesn't acknowledge it as it does with the 06 01 01 01 sequence, so I don't think it's valid). But it's more granular: each byte controls a single function: it's really 06 aa bb cc. Set aa to 01 and you get full mixer/midi control of the fader section. Set bb to 01 and you get full mixer/midi/plugin control on the rotaries. Set cc to 01 to enable clip mode on the pads and set their colors. And here's the good part: the MW/EP/SP lock to channel 3 happens only if you set all three modes active. If you leave one set to 00 (say, you don't use the pads, or are happy running the faders only in midi mode) then the MW/EP/SP continue to transmit on the proper set channel, NOT on channel 3.
Waiting to hear back from Novation on whether this is fixable, but in the meantime it at least gives me a workaround to play with.