Not many Multi-Player (MP) missions around, so no tutorials that I know of, sorry. However, there are several MP missions in FSX - mainly race missions - which you can load from the Multi-Player tag (not Free Flight or Missions) on the main menu. So, you can play these missions as host with other players linking to your PC (via local net or web).
I've decompiled some of the MP misions' spb files into xml (using the spb2xml converter) and viewed the missions with Jim Keir's FSXMissionEditor (FSXME). You can then see how the original developers made up these fairly simple race missions. Hope that helps...
Good Luck, Claudio - and let us know how you get on!
Cheers - Dai.
Thank you very much for taking the time to answer my post.
I discovered it is quite easier to prepare a scenario triggers proximity effects on the mission and fly line with my colleagues, that allows us to track changes and improvise fly it several times from several different paths.
We are now seeing the issue of weapons for the multiplayer mode (without resorting to tacpack vrs) and it is an issue that we have very clear how it works yet and is truly indispensable to the realism of the mission.
Greetings and thanks again drdavid.