re:Radius Proxy

Hi, Is there anyway to run a program or a script when the user request for authentication is rejected/accepted? If this is possible then can it be done in proxy mode as well? The script or the program that will be run can be passed certain arguments such as user who got accepted/rejected and realm the user belongs to etc. If this feature is not available then I would like to develop one. My requirement is to inform a network element about the status of user authentication. This network element may decide to enforce certain policies on the firewall. Anand.