There would have to be some communication device, ie: Forum PM, Skype, TeamSpeak ... etc ... so you could tell the other person what you are doing, and what you are sending ... and the 2 people would have to have the same assets of the consist downloaded and installed
I don't know much about multiplayer, but imagine 2 people sitting side by side in a coffee shop, or in the same house room, sending trains to each others laptop via the internet
I was going to break my route up into 6 or 7 separate iPortal segments, and drive from:
Harrisburg/Enola to Huntingdon
Huntingdon to Johnstown
Johnstown to Pitcairn
Pitcairn to Conway
Mount Union to EBT/Robertsfale
Cresson to Philipsburg
But as iPortals are configured in a session, and once a session is deleted, the iPortal names revert back to the default names, I would have @ 16 complexly named iPortal configurations