No need to move the motor or the blower. There is an idler between the motor and blower pulleys. You need 2 wrenches to adjust it. One has to be a 3/4". The other, if I remember correctly, is a 7/8. But it's actually better to use an adjustable wrench or channel cocks.
Loosen the bolt that secures the idler with one hand and move the idler itself with the other.
To replace the pump belt, pull the 5/16- 18 x 2.5" horizontal bolt that secures the front of the pump to the Cat rails, then pull up on the pump head. (i.e., Take the nut off of the end and pull the bolt out.) This will tilt it back toward the center of the machine, which brings the clutch closer to the drive pulley on the end of the Honda's shaft, allowing it to loosen.
To adjust a new pump belt, you may have to loosen all 4 nuts that hold the Cat pump to it's plate, and slide it backward some. Pull the front bolt as before, then slide the pump with the new belt on it until you can see part of the hole the bolt goes through in the pump begin to line up with the hole in the pump. Then secure the 4 mounting nuts that connect the rails to the mounting plate. Finally, push down on the pump, so that the hole for the horizontal mounting bolt in the front lines up with the hole in the plate, and slide the bolt through. Then put the lockwasher and nut on it and tighten.