[hociman]

You might be able to achieve this using the GPI, provided you don't use the built-in talkback mic. The way I would accomplish this is to set two (2) channels to the same analog input. Channel X would have the mic input routed to omni output 7. Channel Y would have the mic input routed to omni output 8. If you had two switches connected to GPI inputs, then you could configure switch one to turn on channel X, and switch two to turn on channel Y.

I work with people who use the user defined keys for transport control. You have to get used to the responsiveness though, as they can be more of a hindrance than a help when the deck goes flying well past where you wanted to shuttle to.