session management

Currently the default Acceptor implementation expect the sessions to be pre-defined in the config file. Is it possible to dynamically create sessions after the connections are made? My plan is to have some kind of authentication and I want to load session dynamically. Any quick suggestion or example code available somewhere?

My goal is
1) Start aceptor using quickfix SocketAcceptor
2) a way to get the logon message to the message handler
3) the message handler then create the session or start the session

Thanks for the help in advance.