Hi All,
My son is nearly 9. In late 2008 I noticed he was having problems with reading & writing so started him at speech pathology to assist him at school. In April 2009 he was diagnosed with epilepsy after a grand mal seizure. His first medication caused his depression to surface (or made him depressed - one or the other). He tried two others and both he was allergic to. He's now on Clobazan. In the meantime, late 2009, he was diagnosed with ADHD. Until they sorted the epilepsy meds, they wouldn't put him on anything for ADHD. He has really struggled this year (Yr 3) at school and finally been put on Ritalin. Unfortunately he became worse and we didn't see much improvement in his behaviour & concentration. Nor did his teachers. He was put on Strattera and it worked fabulously... up until he broke out with a bad rash - he's allergic! So now we're back to waiting. The rash needs to go down before we try dexamphetamine or a stronger anti-depressant.. in the meantime, he's threatened to leave home, threatened me with a knife, threatened his dad with a hammer and this is all in one night. I have to say, I'm struggling to keep my sanity - and my heart is breaking for a little boy who is so unhappy and not himself! Any behaviour modification suggestions or ideas are welcome!!
I feel for you so much! I know what it's like to feel totally helpless because you can't help your child that you love so much! But hang in there! It WILL get better! Just keep trying...you'll find a medication that works for him. 
What are his main ADHD symptoms? My son is soooooo hyper and impulsive that none of the behavior techniques worked without at least some medication on board. Hopefully your son doesn't have the same problem!
Some behavior techniques that work for us are 1. Give him LOTS of warning/notice before expecting anything of him. For instance, if we're going somewhere I always tell him way ahead of time and usually more than once. I usually say something like "In 15 minute we need to leave", "5 minutes" etc or if I expect him to stop watching TV I'll tell him "after this show we're turning it off" It seems simple but if I don't do this for him he melts down!
2. I try to give him choices when I can because he can feel more in control (when he's really not, but it makes him feel better!
) If I need him to brush his teeth I'll say "How many minutes do you want before you brush your teeth?" (with around 15 being the max). Whatever he says is how much time I wait. He can't really tell time yet so that helps! Another example is I'll say "do you want to put your clothes on or brush your teeth first?" I don't really care which one he picks as long as he does both.
3. Something that's working very well for us right now is the marble technique. Have you heard of it? There are many different variations so you can do what ever works for him.
Good luck and I hope things get better for you soon! 
Thank you! Just today he's started an anti psychotic drug just to make sure he doesn't hurt himself, his sisters or his parents! It's been an awful day.. I keep feeling I'm over medicating and I think today I've realised just how serious his condition is and potentially can be, so it's been distressing. I picked up his new medication (instigated by the leading psychiatrist at the Kids Hosp at Westmead) and he's due to take the 2nd one soon. He got quite sleepy within the first hour, but seems OK now. It doesn't stop the ADHD, just the feeling that sends him over the edge.. wanting to kill us! It's a short term fix.
I do give him lots of notice and use a rewards system (although rewards systems are usually short lived). Often I'll tell him the night before what expect in the morning and often that works.. particularly if I can focus on something he can look forward to. I need to use the 'choices' more often - I've stopped saying "no" to things and deflected/diverted him instead onto something more in the direction we all need to head.
Not sure what the marble technique is?
Julie.