Quick answer is no, its not something BSU faces all that often. None of the WAC teams ran a 3-4 as I recall. I think TCU plays a 3-3-5, but that's not quite the same thing although the stunt/coverage packages will probably have some overlap with a 3-4.
But the BSU defense is very dynamic and does play some 3 man fronts, and McClellin is basically a DE/LB hybrid who stands up and drops into coverage a lot, which makes our base 4-2-5 more of a 3-3 or 3-4 in many cases. Point is, our guys might not see much of it in game-time situations, but it will hardly be foreign to them or the coaches.