Hey, Ableton Link works wonders for midi.
Check out a side project I did : Soundcloud.com/version58
It was created all live in real time, improvised, with 3 musicians using Ableton Link. Each of us individually had our own loop stations, and we synced them through ableton link. It was so much fun and really easy to configure.
If you are all in person together, this is a great way to jam. If you are trying to do this remotely over the internet, I think we need at least another 5 years for a smooth programs that would be accessible to the lay-person.
Let me know if you have any questions about it....otherwise the only thing I can recommend is a midi solutions box. If you find something for live streaming internet jams, let me know