[Twisted] Ldaptor - adding authentication to an external ldap directory

Hi! I'm trying to add authentication to an existing ldap service, that is unable to handle authentication itself. I also need to inject an additional search filter for lookups after a successful bind. Using the LoggingProxy example as a start, I was able to proxy the connection. How can I override the authentication part? I also found "svcbindproxy" but it works entirely different, using Proxy instead of ProxyBase class. I was unable to use "handleBeforeForwardRequest" there. I'm working a lot with python but Ldaptor is a whole new level for me. I would appreciate if anyone has some tips on where I need to start. Thank you! Kind regards Kevin