I believe the pulley is aluminum. So you should not be careless. But it isn't difficult either.
First, the tensioner. Don't disassembly anything! You just use a 18mm socket with a long extension arm on the bolt that retains the pully to the tensioner. Press it clockwise, or towards the battery, that lifts the tensioner off the belt that you can then slip out. It's under spring tension and doesn't need to be loosened or disassembled.
Then you'll probably need to remove the coolant tube which is part of what holds the thermostat to the block. if you have never replaced your thermostat now might be a good time.
Then use a three jaw puller, hooking the jaws behind the pulley. The shaft that the pulley is on has a dip in the end so that the puller shaft can sit centered in it. Then using a wrench crank the puller down until the pulley starts to move. You might need a longer handle than a standard socket wrench to get it moving, but it will start to come off. Just take your time and make sure the arms don't slip off.
i'll be doing mine as soon as I track down a new thermostat.