This sounds rather like it might be a custom development task and so we may not be able to offer too much in-depth assistance for this one, but can you clarify exactly what you’re aiming for here?
Do you want to expose these private events to a select audience – how is that audience defined if so (any user who is logged in?) … what are you picturing exactly in terms of blocking out time?
Much simpler then that. We just want to show an event like “Closed for Private Party” and not sell tickets. Which the more I think about it would be simply adding an event with no cost and no ability to register for it.