I'm very interested in this as well (I just finished reading thru the 40 pages specifically looking for this info and did not find it). One of my 2.5 week old chicks has just developed cross beak. I lost 6 of 15 chicks already due to shipping problems and would like to do everything I can for this chick. I've found some success stories with parrots having their beaks pushed back into place with therapy, rubber bands and cable ties, etc., and it seems that if it's caught early enough (at least in parrots), it can be corrected.
This is one site I found, there are detailed instructions and photos of a scissor beak correction in a cockatoo:
http://www.harrisonsbirdfoods.com/avmed/cam/14_gastrointestinal.pdf
I read on a different site that if the beak can be pushed back into alignment with a finger (again this is dealing with parrots), it can be successfully corrected with physical therapy. That site recommends slightly overcorrecting the beak when you push it into place - if you do it properly it will be slightly uncomfortable for the chick, so they recommend giving it some sort of treat afterward. The site says to do this at least a few times a day. It recommends this treatment for chicks, as once they reach adulthood, the beak won't be flexible enough for this to work.
I wonder if the success stories are in parrots rather than chickens because parrot owners are more willing to seek vet care, or are parrot beaks easier to correct due to their shape or some other factor. I don't see how I can possibly get a rubber band to stay on my chick's beak, but I'd like to try banding it together at night. If anyone has any experience doing something like this I'd love to hear from you.