You'll have to remove the belt, belt tensioner, and unsecure the power steering pump, among other things. I highly recommend getting the Snap-On 13mm swivel head extension to access the water pump bolts - while I still needed to strip down the front of the engine to change out my H2O pump, it made it much easier to access the bolts.

See:

http://www.peachparts.com/shopforum/showthread.php?threadid=6640&highlight=pump

http://www.peachparts.com/shopforum/showthread.php?threadid=76303

http://www.peachparts.com/shopforum/showthread.php?threadid=71492&highlight=m103+water+pump+bolts