I know for me, being ADD/ADHD is a big obstacle when it comes to school. What I've found helps me focus best is very loud music played directly through headphones that completely cover my ears (ones like these, they even come in cool colors if you're willing to dish out a little extra money http://www.elitalice.com/wp-content/uplo...phones.jpg ), and a desk to sit at with nothing else distracting in the room at all. A completely quiet, empty room with just a desk facing the wall. If my work is on the computer, then that computer has to be facing me, so I can face the wall. I tend to listen to Drum n Bass, because I crave the deep thump and rise and falls that it brings. Some kids may prefer softer things, like classical or trance (trance is more fun than classical tbh ) , but having another thing in the background "distracts" us from thinking about unimportant things.

Like, for me if I'm not listening to music while I'm doing my work, then I start thinking about stupid things. About how my ears are ringing from the silence. Or are my shoes tied, my shirt is bugging me, just random things that aren't important. But with the music playing, I'm oblivious to external stimuli.

If he's having trouble with the actual homework, like if it's reading, try alternate reading style (that's what i call it lol). like you read one paragraph, he reads the next, etc. Or you read all dialog from one character, he reads dialog from the other character. Extra characters are a toss up. If you make it into a game, he'll be more likely to focus on it and want to get it done to "complete" the game. :3

Hopefully I helped touch on the ADHD side of things, as often I've noticed they can coincide with one another. He'll want to get up and run around from ADHD and from SPD, but if you can combat one at a time then the other shouldn't be so bad.