I just used 2 pry bars to get the stock pulley off.
BY THE WAY- make sure you put the lower timing belt cover on before sucking the damn pulley onto the crank all the way.
Normally you can put the timing belt sprocket on and do the timing belt, then the cover, then the crank pulley/harmonic balancer... its all 1 piece with the new ATI unit, so you need to make sure you combine those steps. I had to cut the s*** out of my cover to get it fit with the pulley on there (so I could use my timing marks). You really don't want to have to pull the pulley off after putting it on.