If I'm not too late on suggestions, I say you track all three guitarists and get really creative with automating the panning on their tracks. Having their tracks move around a lot across the field. Would be really neat. Like, not in a phasing way, but have one guitarist be hard left, and then when he's suppose to be "up front" quickly change the pan to the center or something, and then back to hard left or over hard right, catch my drift? Basically orchestrating the track's pan for the entire album. It could end up being very tedious, but I'm sure it would be worth it in the end as far as production goes. Also...it will help a TON if they all had different sounding amps. Don't let them use the same amp for all of their tracks. Unless one of them has a great amp and the other two have POS amps. Heh.
~006