Serpentine belt replacement

I need to replace the belts on my supercharged V-6 Buick Riviera. The factory shop manual details how to disconnect the engine mounts and lift/lower the engine, which I can do. However, when it comes to replacing the belts, it simply says remove and replace! Now, I realize there are tensioners used to maintain belt tension. My question is, how do I release the tension supplied by these tensioners? My "common sense" says to use a socket/breaker bar to move the tensioner in the proper direction, but unless the threads on the pully bolt are "backwards", I worry than I'll just loosen the pully, and nothing more. Please advise me on the proper way to do this.