I would like to use my Firestudio and Garageband to make a live recording of my band at a gig. My thought was to combine direct feeds in groups from our Mackie 24.4 board with a stereo mic setup back by the FOH board. Is there a simple way in Garageband to adjust for the delay that we will have between the board feeds and the mics?

I would put a delay on the board tracks from anywhere between 3 and 5 milliseconds at mixdown (or post session, at any rate). Set the mix to 100 percent wet and the feedback to 0 percent....experiment a little until you like what you hear.