Please see the following links for help with Chewing...

http://www.dogstardaily.com/training/errorless-chewtoy-training
http://www.dogstardaily.com/training/destructive-chewing
http://www.sfspca.org/sites/default/files/kong-stuffing.pdf
http://www.clickertraining.com/node/83 - You may need an account to see full training instructions in the www.clickertraining.com library. Signing up is free, only takes a a minute and will provide you access to tons of great training resource articles!