First things first. We are running a contest here and because you were one of the first to post in the forum since it started you have won a free copy of the book! Just send your address to info(at)bestonlinehighschools.com.
Now on to your question. In order to be successful in an online environment, you need to be motivated to succeed. It is most certainly an important criteria for success.
Can you list things that your son is motivated to do?
What you need to find is a program like
Laurel Springs School that can provide additional support if it is required. There are few out there like that.
I think in order to be successful you would need to explore schools in that direction.
However, I would be happy to pursue this further. Ask more questions and I will give more answers!
Tom Nixon