I did this about a month ago and had all the sizes for everything written down, but lost them somewhere... Sorry.   My engine bay will look a little different then your probably.  The Previous owner installed the intake on mine, so I took the air box out for the install just because there is nothing holding it in, it is just sitting there.  Other then that it should be the same for you on a 4.0 XJ.  Mine is a 99 XJ just for your reference.

Here is a pic of the Engine bay with the pump circled:



A closer picture from up above:



The first thing that you will need to do is to loosen the belt on the pulley.  To do this on all you do is loosen this bolt that is circled. It will move the tensioner pulley down giving you slack.  Keep track of how the belt is ran because you will need to put the belt back the same way. 



Next step is to unplug the hose from the resivour.  That is on the back side of the power steering pump. You will need to get a pair of pliers and pinch the medal ring around the hose.  Then once it is pinched, work it down the hose so it is no longer pinching down the plastic piece that the hose fits over.  

On a side note this plastic peice is not the most sturdy.  SO when installing the new pump be very careful not to break this off of the new one.  I installed the hose first before anything else so I could move the pump around and not just shoving the hose on.  Also when installing the pump, they sugest that you put new hose on too.  I didn't, but they you probably really should since it is already torn apart.

Once the ring is pulled down just pull the hose off.  When you do this all the fluid in the pump will leak out, so be prepared for that.

Here is the before and after pics:





The next thing to do is to take the hose off the top of the Pump.  This one will be screwed off the top.





Now the only thing to do is to take the 3 bolts off holding the Pump on.  1 and 2 are on top, but #3 is on the bottom.  Also in this picture is bolt A, which is the bolt that you have already loosened for the tensioner pulley, just to give an idea of where you should be looking.



Taking these 3 bolts out is some what tricky you will have to move the pulley around to where the holes line up with the bolts so you can get a deep socket wrench in there to get them out.  Here is a pic of one of the bolts almost all the way out so you can it fitting through the hole. 



After you take those three bolts out the pump should just come right out.  You will then need to take the pulley off before you can take the pump in for your core charge at the store.  I bought this tool to pull it off.



This is what that pulley puller will look like when you have it on the pulley ready to pull it off:



This is what the new and old one look like together.  I bought a new pulley because my old one was plastic and broken a little.  If you do this, make sure you request a metal one, you can thank me later. 



That pulley puller states that it is also an installer.  I used it and ended up breaking the pump, sooo.  When I took the pump back to NAPA and told them what happend they gave me a new one and installed the pulley on it in about 3 minutes.  So before you spend an hour getting pissed and breaking your brand new pump ask them to do if for you and it will save you a head ache.  Also I think that you can buy a pump with the pulley already installed.  So when you are buying a pump these are the questions to be asking:  Can I buy one with a pulley already installed?  Can you install the pulley on the pump? 

Hope this helps.  Total install time is about 45 min if you have the new pump and pulley installed on it.

-- Edited by aci4369 at 13:59, 2009-01-17