How to replace the power steering pump in a jeep grand cherokee 4.7 1999

Pretty simple unbolt and bolt back on operation. One thing though is most rebuilt pumps come with no pulley and you will need a machine shop to transfer yours to the new one. A special tool is necessary to do that so don't attempt it without the tool. If you haven't ever done this work, get a manual such as haynes or chiltons...it will not only help you there but in the future too.
After it's installed, fill the reservoir with power steering fluid and gently turn the steering wheel all the way in one direction (running) and then all the way in the other direction. Re-fill the reservoir and do the same again 'till the air in the system has been purged. Some fluid foaming and slight noise is normal but should disappear after a half hour or so.