MTP Correct.
You must first loosen the bolt in the center of the pulley for the A/C tensioning pulley, then screw out the other bolt you mentioned.
You don't have to loosen the pulley center bolt all that much. Tap the other bolt with a wooden stick or something, and it will work past the grunge to let the pulley de-tension the pulley and belt so you can remove it.
You can thread the alt belt on over the fan a blade at a time until it's in position. lever against the water outlet to tighten the alt belt. remember there are three bolts on the alt that should be loosened/tightened when attacking this belt.
BEFORE you install the alt belt, wiggle the fan/clutch assemble and see if you detect ANY wobbling of the pulley on the end of the waterpump! If it moves, the bearings are on the way out, and you need to get a new water pump soon! Running like this can result in a helicopter revue as your fan lifts off the broken pump shaft and decides to eat your radiator!
Replace and tighten the A/C belt afterwards by tightening the other bolt first, and then the nut in the center of the pulley.If you wish to minimize dowwntime, you can stow an extra belt for future use, but it gets really dirty, and I carry tools with me, so changing it isn't a big problem.
All better, on the road again!