M.L.
Dr. Sears has some great discipline advice. His emphasis is on behavior shaping by helping the child learn their value and to catch them doing good, a lot of positive reinforcement. It's not downplaying the offense, but it's giving the child more ways to feel valued as well.
My son will sometimes say he's a bad boy when he gets in trouble. We tell him he isn't bad, he just made a wrong choice and now he knows better, he can try extra hard to make the right choice next time. Then. I remind him of all the good things he did that day. It helps him have the confidence that he can overcome certain things, and we encourage him to be his "best self".
He is some interesting advice on apologize and teaching that, and modeling forgiveness that maybe can help:
http://www.askdrsears.com/topics/discipline-behavior/mora...
also, I think the techniques on modeling behavior and how to help the angry child have tips that could work as well:
http://www.askdrsears.com/topics/discipline-behavior