How do i make a map soo only a people/server has paswords can play it, if no pass/code <--(or whatever) you get transported into a room with nice texture saying its only avalaivable on a certain servers?

Ive been looking for it on google for hours, now its 3 AM and im sick of googling and drinking coffe. I did search for it on this site too since its helped me before but without any luck.
I doo bet that ive havent looked furthere then my beard and ive missed it...

And since it has been done before some one is bound to know how to, know help i can only go to bed and hope some kind fellow will help me while i sleep...