Security: how to correlate services to users ?

Hi,
I've run a couple of times into a situation where you have more than one
service at a gateway and different sets of users.

Classic is management users and remote access users.

What are the options to have this implemented ? Is there a way to have
multiple "local" databases ? Or to mark the tacacs request to indicate a
given set of users is intended ?

I've resorted to multiple tacacs servers, or tacacs and local, but is
cumbersome...

Appreciate any hints.
-Carlos

-- 
Carlos G Mendioroz  <tron_at_huapi.ba.ar>  LW7 EQI  Argentina
Blogs and organic groups at http://www.ccie.net