Going from 2 to 3-man mechanics isn't all that difficult. The only thing that you will probably have some problems with is switching and rotations to start with. The problems I have when doing a 3-man after the majority of my games are 2-man is worrying more about where I am supposed to be than I am about making sure I call the game.

Make sure to get a good pregame with your partners and decide exactly how you are going to switch on each situation and how you are going to rotate. That way when a situation comes up you've talked about it and know what everyone is going to do.

I would think that the big issue you would have would be switching back and forth from FIBA to NCAA men's.