Not want to hijack the question, but if you run Apple Mainstage on the MacBook it has a plugin called Playback that i.e. is a file player. Assign any pedal switch of choice to trigger its playback over MIDI. If connecting a USB cable between the Axe and the Mac the Axe can work as the lappy's audio interface. The Playback plugin also follows tempo (if set up that way) and adjusts file length to tempo with time stretching in the same manner Apple Loops work. One related thing I don't know though and that is whether the Axe is able to send its tempo as MIDI Clock back through the USB cable (last time I tried it did not work, although it worked as a charm the other way around; Axe picking up MIDI Clock coming in through the USB)
