Hello !
So, here's the trick :
The meeting stone takes time to appear, so in Outland, just stand on it with your flying mount, and go up at the maximum in the Sky.
Then, dismount, looking at the sky if you have a performant computer( yeah, that's important ) , and at the last moment, use a slow-fall thing to don't die, but to be still in the stone. ( Or just be BoP by a Paladin, or use the Focking Bubble, or .... ^^
And tadaa you are in !
I've found that by myself of course !
And sorry if my English sucks, i'm french. ( Yeah, a looovely frog )