Some i've removed came off without needing a puller and others put up a fight. Remove the nut with an air impact while the belt is in place to help grab/hold the pulley. Once the nut is off, remove the belt and then the pulley. Do you know how to swing the tensioner out of the way so you can remove the belt? Should be obvious, but speak up if you need details and someone will chime in.
I use a 3-jaw puller, which usually works for me with the thermostat housing in place. If you've been contemplating having the housing off for whatever reason, you may want to do both at the same time. In some cases it was a puzzle to get the pulley free from behind the housing. it can be an entire other job dealing with housing R & R, so if it's not leaking, I'd try to leave it.
Check the snout (top/bottom) to see if it's wet/oily and consider having the pulley off as a chance to replace the front seal. Inspect the belt and replace if worn/cracked. Gently rock the shaft left/right to see if the coupler is ok. You may as well check the oil level while you're there - see:
http://www.sccoa.com/forums/showthread.php?t=103121&highlight=supercharger+oil
Count the threads showing before removing the original pulley to give you and idea when the replacement is on all the way and lined up with the jackshaft pulley. Line up the slot in the pulley with the key and slide the pulley on by hand, then use the nut to pull it all the way on - install the belt and tighten.
In a simple/quick example, one pulley comes off and another goes on. If you do all the work mentioned above, it could also involve having a new belt, thermostat housing gasket, snout seal, supercharger oil and a replacement fill plug (if the old one is/gets damaged during the process). Of course, by having those ready to go before starting the job, any downtime is minimal.