Cisco, Dell Authentication for Admins

Hello, Just looking for guidance to the easiest way to handle Privilege-level access to Dell or Cisco Network hardware, such as Routers, and switches. Currently I have freeRADIUS running for 802.1x WiFi authentication, which accesses a Kerberos database. i only need to identify a small group of Network Engineers as Admins and allow them access to the devices, but nobody else. What's the easiest way to accomplish this in freeRADIUS, or if I need to use another method? I'm not worried about command Authorization at the moment, although that would be a "nice to have". Thanks! -brconflict