Proxy when database value is set

I've achieved the following: - A user with a username which contains a realm logs in. - Freeradius checks some radius request values like calling-station-id etc. - Freeradius will give a reject or accept depending on the above query. What I cannot achieve is: - Freeradius must proxy to request to a token server but only when it authenticated the user successfully. Any ideas? Thank you in advance. Regards, Johan van de Laar