Could do it several ways....
The easiest way I can think of is make it a purchase for someones playerhouse/guildhouse. Have the home owner be the only one with the access to open/close the spar entrance, and start the spar. It will let players invite their friends, guilds, etc and divi teams on their own. Make the spar floor 488x322, and the layout like this...Once again I'm willing to level it for you guys or help out in anyway I can.