Not knowing for sure what year or what size engine your Cherokee is makes it a little more interesting. First off, here is a site that [http://www.ehow.com/how_5755230_change-steering-pump-jeep-cherokee.html|explains it well] and I posted the power steering part of the service manual on my file server for you to download. It explains in detail how to do it. Good Luck and let us know if you need further help.
[http://www.keepandshare.com/doc/2725287/jeep-cherokee-steering-1-762k?da=y|Power steering part 1]
[http://www.keepandshare.com/doc/2725288/jeep-cherokee-steering-2-182k?da=y|power steering part 2]