i've actually seen something like this attempted, but can't find the site.
it went something like this:
1. use an exacto knife to cut a rectangle from the interior of the book (make sure you leave edges)
2. mod podge or elmer's glue all of the pages to the back cover
3. let dry, but do not close the front cover!
4. when dry, cut felt to fit area around the open rectangle, and glue it on. if you're feeling ambitious, you can also line the interior of the box part with felt.
hope this helps and is clear enough to understand - let me know if any of it is confusing.