Online or single client (offline)? Dolphin supports multiplayer just as the games it runs do - split screen on the same host. Online multiplayer will likely come to pass in the future, but don't get your hopes up.
i have a real copy of PSO ep. 1&2+ and gamecube (and wii not sure where's the GC at), is there any emus that support the broadband accessory and reads from CD drive (i want to play schthack private server