Certainly no "out the box" solution available.
I did for example play around with saving user progress to a MySQL database rather than the localcontent solution used by Squiffy. Just doing that required a lot of reverse engineering. So getting a true multiplayer system set-up would be a lot of work.
This was brought up in Quest...
There may be some ideas there...
But, are you talking about a network type game???
Or several people around the same PC???
saving user progress to a MySQL database rather than the localcontent solution used by Squiffy
That sounds fun to play around with!