Board Thread:Support Requests - Getting Started/@comment-257763-20130904052523/@comment-11733175-20130904120137

With the tools a user has available to them, it's impossible. The only wikis that are allowed to be private are internal staff wikis, such as the various wikia-dev domains which I assume are used for development, the internal vstf wiki which will have various vstf relevant things, and the community council wiki, which you need to sign a nondisclosure agreement to be able to use (after being invited to the council). They're all hidden for reasons varying from legal to not wanting to give away what's being developed by Wikia's engineers until it's ready for public release.

What you can do, it write the content before the book is published but not post it on a wiki. If it's not in the public domain, it can't be leaked.