I've just posted the steps for replacing the water pump on a N/A 3800 engine a couple of days ago. Here it is again:
0. Empty coolant to below pump level
1. Disconnect negative battery terminal
2. Support engine from below with a jackstand
3. Remove belt, alternator, coil pack
4. Remove engine front (passenger side) mount
5. Remove water pump pulley (* see below)
6. Remove water pump
7. Install new water pump using a new gasket
8. Install pulley, engine mount, coil pack, alternator, belt
9. Reconnect negative battery terminal
10. Refill coolant
* The 4 pulley bolts are hard to open/close, because the entire pulley tends to turn instead of just the bolt. The best way is open one of the water pump bolts (the top one that'* just behind the pulley) with an open-end wrench until it holds the pulley in place, and stops it from rotating freely. Then opening the 4 pulley bolts is no problem at all.
Your car may be a little different, I have no experience whatsoever with the */C engine.
Hope this helps