HOWTO Negotiate a Creative Commons License: Ten Steps

Step 7 Write it on a wiki.

Pre-emptively license it CC. Write your book on a wiki before you begin negotiations. Give the wiki a CC license. The wiki, or some other electronic version, is a different work, and therefore if you end up unable to convince the publisher, at least the wiki is CC. Other authors we spoke to simply published their manuscript on a wiki and gave it a CC license. While a lawyer might be able to give you an opinion about whether you can post a manuscript for a book and CC license that manuscript retroactively, I think it is safer to pre-emptively license your wiki.

Image below CC caseywest