Time outs never worked (at all) for our Asperger kid. 123 Magic: a total disaster. These increased anxiety without ever helping us manage negative behavior. Your mileage may vary, ours is surely a fairly specific case.
What has been effective for us is for the parents (us) to give up the idea of "sending him to his room" or "putting him in time out" to deal with the fallout of behavior by himself. Ours needs some very hands on teaching in the moment. (Discipline means teaching, anyhow.) This is a ton of work, but worth it.
We have had to spell out what behavior is expected in advance, and have him rehearse that behavior when he and we are calm, enough times that we are sure he knows what to do and how to do it. If there's an infraction, we try to stay very even keeled, and go over the problem again, ask him to make a better choice, and ask him to repair the damage he did (by apologizing sweetly and sincerely, or cleaning up his mess, or otherwise working to fix it). This ties consequences directly to the infraction, and makes it about teaching a better way rather than about punishment.
The other main thing is that if he fusses about something, it's taken away. (If he whines for Wii or doesn't turn it off when he's supposed to, if there is nagging for dessert... not going to happen. If he and his brother fight over the object, it goes away, usually for at least 8 hours and up to 24.) This keeps the taking away of objects to a minimum, because it's only fussed-for things that have to go. And if it's fussed for, it's the one that matters most to him anyway.
We have more recently done well with a system that awards points for desired behavior, with privileges (things like dessert or choice of beverage at dinner or Wii time) being contingent on staying in the positive number territory. Points are taken away for disrespectful behavior, so he can end up in negative territory and lose his privileges. It is very engaging to his mathematical sensibility and seems to be working pretty well.
HTH,
DeeDee
