You could try the Bitter Apple method described in the articles at
www.Leerburg.com (or better yet, get Ed's basic obedience video). I have not tried using Bitter Apple and I am not crazy about the initial steps suggested with it (I.e., soak cotton balls in Bitter Apple and force them into the pup's mouth and hold their mouths shut for a minute or so). I don't like the idea of just doing that out of the middle of nowhere on a pup, but I am a candy ass that way.
I used those yellow bulbs of lemon juice. Palm the lemon juice and when the dog gets gnawing, quickly and silently give them a good shot of lemon juice. Make sure the bulb is well in their mouths--you don't want to get any in their eyes. Once they connect the scent with the lemon juice, you can squirt a few drops on you and others' hands and the dog will leave you alone. Worked very well for my young kids. Same basic idea as the Bitter Apple, I just would rather use lemon juice than Bitter Apple and rather use a reactive negative enforcement than a random, proactive way.
Others may have other ideas. To Lyn's point, redirection makes the most sense to me if you've not tried it yet. I should have stuck with that way longer, I just didn't have a lot of room for error with my small kids and my dog was quite the nibbler.
I would check out the Leerburg articles and videos first if you've not done so, in any case. They tend to present perspectives on about any issue you may have, from collar types to PITA puppy issues. The basic stuff seems to be regarded as more right than wrong for new folks like you and me.
