I used behavior charts for almost 3 years in conjunction with some other behavior modification techniques.
They worked so miraculously here that we actually went from having Dylan with an ODD diagnosis to having it removed from his Axis because he didn't any longer fit the criteria (and we medicated his Bipolar properly).
It took alot of work, alot of time, and it didn't work in a week. It was a very slow process and weaning off was a very slow process, but years later, and he's only 10, I don't need a chart for anything. He does ALL by himself, without having to be told twice or getting any reward.
I would post more info here but it would be a book. If I can help in any way, please PM me.
Good luck,
Janna