It will help to say what blower your running and if it drives the water pump or not. I had a pulley made to bolt to the front of my water pump, then ran the alternator off a bracket on the passenger cylinder head. That wasn't very expensive, but uses a cog on the blower and a gilmer style on the alternator.
Are you trying to run it all on one serpentine belt? The more info you give the easier it is for someone to help you.