I don't understand if you want to emulate WinMX or build a web based interface for a WinMX client... If you want to build a new interface to a napster-like p2p network, start from a mldonkey server and build a web interface to it (or use its native web interface). MlDonkey can speak EDonkey, Gnutella1/2, Soulseek, DirectConnect, Bittorrent, Overnet and Opennap.