You need a wrench that fits the hex on the fan shaft. Then you need a pair of channel locks that you can grab the pulley and hold next to the timing cover. The fan is removed by turning the wrench clockwise while facing the front of the engine. Some additional info can be found at: http://www.dieseltruckresource.com/dev/showthread.php?t=62880
I refrain from using a any form of a chisel due to the weakening effect it can have on the mounting hex shaft.