Using Link to sync multiple Macs?

I've looked thru the Forum and at Ableton's site, but I can't see anything that tells me how to sync Max on different computers together.
I've installed the Link package on both Macs; both are on the same wifi network; opened the help files and gotten different patchers changing tempo together on individual machines. But I have no idea how to get both Macs seeing the same Link Timeline.
I opened a Link compatible app on my iPad, but it said there were no other sessions running.
I'm obviously missing something, but what?!

What I want to do...
The same patch running on 3 different Macs. The patch has a note quantise function so that a triggered note is delayed until the next clock pulse. I'd like to have all 3 Macs following a single clock so that note ons are (more or less) synchronised across the 3 machines.

I _could try using midi sync, but it would be much neater in the workshop space if I can do this wirelessly.

thanks for any pointers...