exec external script on successful proxy authentication

[Mike <needacoder@gmail.com>]

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?