i assume you mean by using ServerSocket in AIR. ServerSocket creates a TCP server (listening) socket. RTMFP uses UDP. ServerSocket can't be used to create an RTMFP endpoint.
Adobe Media Server (AMS) implements RTMFP and performs the same peer introduction services that codename Cirrus does. AMS is available for purchase or by the hour on Amazon Web Services. see http://www.adobe.com/go/ams for more information.
the RTMFP base transport protocol is described in http://tools.ietf.org/html/draft-thornburgh-adobe-rtmfp . however, the Flash-specific adaptation for RTMFP, including the "cryptography profile" we use and the mapping of Flash communication to RTMFP flows, is not yet publicly published. see section 188.8.131.52 for an illustration of how RTMFP P2P introduction works, as practiced by Cirrus and AMS.