I mentioned in another thread about many people having great success with a leg band - WoundWear brace (A-Trac)
http://animalrehab.on.ca/index.asp?tag=braces
Here is another link to review
Dog ACL CCL Ligament Recovery Without Surgery No TPLO canine hip dysplasia surgery, fho, tpo, jps, thr, dog surgery
Here is a yahoo group you can join to discuss ACL tears
ConservativeManagement : Canine Conservative Management
Our Newf Cassie tore her Cruciate when she was young, then a partial tear in her other leg at 10 years of age. The partial tear we just allowed to heal naturally. She is now soon to be 12 years and has no arthritis in either leg and very flexable :)
Good luck