as said your gonna need the host software, as otherwise its just not possible.
sega wont release it as then there would unofficial 3rd party pso servers popping up and also with no way to choose the server your connecting too (ip etc) then you would be stuck on pso` sega servers
maybe if a modified version of thw Warp Pipe Project was used it could be possible to play the multiplayer online this way.. but it would mean some sort of unnoficial append disk
put bluntly its not poss with ep1&2 but is with ep3