[Plugin: Redirection] Redirect all URLs under one directory

I’ve been using the Redirection plugin for my site and it’s wonderful! I have one question, however – how could I use regex (or other method) to redirect all URLs that are below a certain directory to a page?

For instance, I’d like for anyone not logged in that tries to access http://mydomain.com/documentation/ or /documentation/phonenumbers or /documentation/tech/office (anything after /documentation) to redirect to a login/registration page.

I’ve tried /documentation/* and looked through some basic documentation for regex but it’s still not clear to me. I have 45+ pages to redirect and doing it manually for each page, while doable, is a daunting task.

Thanks.

http://ww.wp.xz.cn/extend/plugins/redirection/