I dont remember too well what the commodore 6s look like but there should be 3 water pump bolts and one of them should also serve to anchor the strip of metal that has the tension adjustment for the alternator, remove the shroud, an assembly and radiator hoses and that should do it, clean the gasket face on the block and give the new water pump gasket a spray with the hylomar from a can (dont go stupid with it though) just prior to re-assembly.
good luck