If your pry bar is too big or too small or you don't have one handy, I've found that a crescent wrench can do the trick just as well. You may have to hinge the alternator up and out of the way to do this, but you can fit a narrow crescent wrench onto the power steering pump bracket in front of the pump itself and use it to pull the pulley back hard enough to tension the pulley sufficiently. I had a 10" Kobalt lying in the back of another truck in the yard, but just about any other could be ground to fit.
Also, a little unrelated, does anyone have a photo of their pump bracket mounted up to the bracket at the left (outermost) bolt? The diagram in 8-15 of technical manual 9-2320-289-20 shows the bolt (12) coming in from the front, which is what the previous owner of my truck SOMEHOW managed to follow, thus ruining my steering pump less than 100 miles after I picked the truck up. My pump bracket has an ear that sits behind the mounting bracket and the bolt comes in from the rear. Possibly a retrofit or jerryrig? Either way, it was mounted wrong, something I should have caught earlier, but that's life.