What we do is have a "word" that is associated with doing something naughty
like chewing anything - we use a sharp "Ah Ah" ... and it is currently in
use a lot with two five week old Jack Russell puppies ... they get used to
it and it soon works. You just have to be consistent with the "word" and
it's use - never needed to touch them at all. Trained the pups' mother this
way when she was a pup too ...