Well, I am a mother of a 2 1/2 year old and an elementary school teacher. The best advise that I give to parents is to set aside a special place (no distractions) and do the homework as soon as your family gets home from school. No TV, movies, outside play time, video games until the homework is done. It might take a couple of weeks to really get your point across but if you stick to your guns and allow no "fun" time until homework is finished, your child will eventually get the point and realize that you are not kidding.
You also might want to begin a reward system at the same time. Everytime there is no fussing, whinning, etc.. then they get a sticker on a chart or a pebble in a jar. When the chart or jar is filled up, they get a prize, treat, or special time with mom and dad. Positive reinforcement is a wonderful thing!
Something that I do for my families that I teach is to pass out all homework on Monday and have it all due on Friday. Let's be honest, things come up during the week that might cause for homework time to be interupted. If parents and kids know the homework in advanced, they can try to plan around it and get more done on one day incase they have church, ball game, family events, etc. The class that I have now is a class that I taught in 1st grade and now have the same crew for 2nd grade. My parents know what to expect and they like my system. If you feel comfortable enough, you might mention your problem to your child's teacher along with the home modifications that you are using and just see if she can change her homework schedule to help your liitle guy!
Hope that you find something to help you!
M.