Cisco VPN :: ASA 8.2.x - Control Access To Different Group Policies On VPN? 

Using Microsoft IAS as the auth server, how do I get the ASA (v.8.2.1) to take different user groups defined in AD, and control access to different group policies on the VPN?  We're setting up the ASA for many different vendors, and need to control access for each vendor with different policy.

For example, Vendor one is in AD group Vendor1 and will only be permitted access to a specific group of defined IPs in our network. Vendor two is in AD group Vendor2 and will only be permitted access to a different group of defined IPs in our network from Vendor1.