exec external script on successful proxy authentication

Dear list, Is there a way to execute a script with the original request attributes at the time of successul receipt of authentication reply from a home server when FreeRADIUS is used as a proxy? We require to execute an auxilary action on successful authentication, but currently have only found ways to do this at the time of request. Also, is it possible to add arbitrary attributes to the proxied response? Something just like preproxy_users, but rather post_proxyusers?