itati, I have a 5yo DS who gets frustrated and angry and would love to bite / hit / kick especially his sister.
I wrote a family law, along the lines of..
"We are a family. In our family we do not
hit, bite, punch, kick or hurt each other. In our family we are always kind, share ..'
Sure you get the idea. Anyway, got them all (including DH) to sign it. When they are naughty I march them in front of it and make them read it or recite it. They HATE doing this. They think if you don't obey the law, you won't be in the family (little do they know we are together forever).
BTW, last time DS bit me (a long time ago) I told him about what would happen if he bit a stranger. I then put him in the car and drove him to the police station, I got him our of the car and at this point he was sobbing uncontrollably. Trust me, he has never ever bitten me again.
I would recommend both - violent behaviour is not acceptable. They wouldn't do it to strangers, they shouldn't do it to you.
Awful little sods sometimes, aren't they??