First off, I really hope you're not playing with your tongue piercing as a means of distraction from the chewing on your lip, because you're going to fuck your mouth up. It will wear down your enamel and cause your gums to recede.
As a fellow lip-gnawer, I can tell you to NOT get your lip pierced under any circumstances. You will end up chewing the jewelry and it will damage your teeth to the point where you will need expensive repairs done. I'm looking at a good $2000+ worth of work that needs to be done and that's WITH insurance.
There is nothing that can prevent it unless you figure out what's causing it (is it just habit or an actual anxiety situation, etc. - go see a therapist and find out) in the first place. Chapstick is a great suggestion. If there's no skin to peel off, there's less chewing involved.
If you want pictures, go to http://www.bmezine.com
And for future reference, nobody gives a flying fuck where you crossposted, so there's no point in telling us. If we're in those communities, we'll see it for ourselves, so what's the point? :)