You want to use IAS to assign a computer to a VLAN based on who is logged on? Not sure you can even do that.
That would require the ability to change what VLAN the ports on the 3750 are on which would require scripting and enable authority or SNMP update access. I don't believe that IAS has the ability to do either.
I think the 3750 can participate in VMPS, but that assigns VLAN's based on MAC addresses.
You can start here:
http://www.cisco.com/en/US/tech/tk389/tk814/tsd_technology_support_protocol_home.html