No you don't pull the radiator. You will drain the engine coolant, remove the electric fan on the drivers side, break loose the bolts that attach the waterpump pulley to the waterpump, and then remove the belt. Then you are free too remove the waterpump. If you haven't done so recently, its a great time for new hoses, belts, and thermostat. Make sure you have a tube of RTV sealant handy and coat both sides of the waterpump gasket ( the new waterpump should come with a new gasket). This guide should help you
http://www.go.jeep-xj.info/HowtoWaterpump.htm