Although I cannot offer much advice about having children with ADHD (my son is 2 1/2, so too early to tell), I can tell you what has worked for me. I have ADHD. I did not know until I was 19 years old that I had ADHD,but learned how to cope long before that. I tried meds once I was diagnosed, but quit takign them because I didn't want to become dependant on them. One of my biggest problems was reading. I could read aloud, not silently. At first, I would get whatever book I was supposed to be reading for school...and and audio tape of it (cd in today's world). I would play the tape and sit with my book and follow along. I would find myself reading the same line over and over without realizing it...so i got a bookmark or piece of paper and as I finished reading a line, I covered it up so I couldn't read it again (instead of uncovering a line to read like a lot of people do). It really helped to have things reinforced doubley...what i mean is listen and read or have something physicall to do...such as count beans. Another thing that helped was to tap my foot or twitch my leg or play with my hair. I am sure your boys do some repetitious activity like this that really annoys you, but if you let it go and allow them to do it without fuss, I think it will greatly help their attention span.
Having ADHD is kind of like this...I used to work in a pizza place (my first job)If i was at the counter taking an order, I could hear the person accross from me ordering food, the people behind me talking about what they were making, the people at the end of the oven talking about what was coming out, everyone's conversation in the dining room, the television in the dining room, the music in the dining room, the talk from the back room, the dishes and things being moved about, the radio from the back room...and it was not white noise. I heard each and every word that was said, but could not process it as fast as it came in. Consequently I was constantly distracted by wherever the newest noise was coming from or wherever any motion caught my eye.
If you are trying to help them with homework, try tapping the paper with your finger or a pencil wherever you are trying to show them something. The movement of your finger will keep their attention to what you are trying to show them without distracting them terribly...and if they don't like it, they will tell you to stop. Another thing to try is 15 minute sessions. The brain remembers best the first and last thing to happen when studying/listening/whatever. The more "sessions" the better. So...have them study for 15 minutes and then get up to get a drink, walk around the room, go outside for 5 minutes of fresh air, then right back to work for a nother 15 min. They may object and say that it takes forever for them to get their homework done, but you can always tell them to try it for a week or two and if it doesn't seem to be helping you can always drop it. Odds are they may find that it works well...they key is to try to find things to keep them "busy" without drawing their attention away from what they are doing or in the case of the book/cd idea that they have 2 things to do at once. People with ADHD are great multitaskers! In fact, sometime function best that way.
Good luck to you. Feel free to message me with any questions.