It's fairly straightforward.
1. Create a new Book file and make it available in ID with app.books.add(..)
2. Add a document to it, using its BookContents property.
3. Repeat step 2 until you're done.
4. Save your new Book.
5. There is no point 5.
This older post -- http://forums.adobe.com/thread/289048 -- shows the basics. The original poster said his script didn't work, but did not get back to the forum and (without actually running it) the script looks fine, so it's safe to assume his problem was something else.