Questions about NoCat Auth authserver setup

Hi, I'm new to the list, NoCat, and LDAP...  whew.
I have recently set up a NoCat Auth portal in open mode, users are 
redirected to an Acceptable Use Policy, accept it, and then can use the 
internet normally. This means that users outside the company can use our 
bandwidth, which is okay temporarily but not in the long run.
What I'd like to set up is an auth server that authenticates with our 
Radius or LDAP server. I have questions on how to set that up.
Should I set up the NoCat auth server on our LDAP server? or can I set 
up the NoCat auth server on the NoCat gateway machine and have it check 
authentication attempt with our LDAP server? Is that even possible?
I know little to nothing about LDAP and don't want to touch our LDAP 
server if possible.
Any help, suggestions, etc... would be much appreciated.
Thanks,

-- 
Matt Miller
Solutions for Progress
728 South Broad Street
Philadelphia, PA 19146
direct: 215-701-6108
fax: 215-972-8109
main: 215-701-6101