It's pretty easy to do. I've done it twice on mine. Once to remove the old one and see that it wasn't bad, then once to go ahead and replace it for good insurance.
Twist the tensioner with a 1/2 drive ratchet and slip the belt off the PS pulley. Then you can easily remove it. The hardest part is getting it by the tensioner pulley. This will be obvious when you get there. To get the new one on, I start with the A/C pulley and the crank pulley. Get those on first. It may take a long tool (like a LONG screwdriver) to help you here. Snake it through the pullies like what's on the routing diagram under the hood. Finally, get it ready to go on the PS pulley, then twist the tensioner and slip it up onto the PS pulley.
The hardest part is making sure it's correctly aligned on each pulley. The other hard part is getting it back behind the tensioner pulley. Frustrating sometimes, but it'll go. It may be easier to remove the tensioner...just depends on your style. Leave yourself about 20 mins to go slow and careful.
After you have it installed, bump the starter a few times and check to make sure the belt looks like it's tracking okay. Then you can start the engine and call it done.
