As he said, 13mm wrench for the tensioner. Take off the splash guard (2 10mm bolts I think?) in the wheel well to be able to go from the bottom. I believe the PROPER way to install the belt is from the top, putting it on the WP pulley last. However, if you're doing it yourself, it's best to drop the serpentine belt from the top, get it on everything except the crank pulley, pull the tensioner and quick slip it on. It will probably be barely hanging onto the WP pulley so make sure it's all the way on that...