Temporarily Set Network Site to NoIndex


I have more of a platform related question. I'm in the process of setting up a WP Network install site and I'm wondering how I can go about "discouraging" search engines from indexing the entire site (domains, subdomains, etc) until the site build is complete? I don't see a setting in WP much like is in a standard install. Can this only be done through robots.txt or .htaccess? If so, can you provide me with some guidance?