Im looking for information on changing the waterpump on a 2000 DeVille, if anyone knows of a guide, or would be kind enough to outline the process here, I would be greatly appreciative.

Disengage the water pump drive belt.
Remove the pump cover.
Use water pump cartridge removal tool to loosen cartridge. It is not threaded (cam locked). It only takes about 1/8 turn clockwise to loosen.
Reverse the instalation.

I saw on ebay, you can buy the gm toom for the removal and installation of the Northstar water pump. It is made by lisle and runs about $20-$25

The Lysle socket is stamped steel (heavy guage sheet metal), that's why it is so cheap. I have heard some people say they had trouble with it. Other said it worked fine. A machined socket from Snap-on runs about $75 but is much beefier. You can rent one from caddyinfo http://www.caddyinfo.com/toolrental.htm. here is a picture of one I made but haven't needed.........yet. http://www.geocities.com/grandolfo/

If you need any more information then this do a search. There are a lot of posts here about it.