If the kids are working on specific IEP goals, the teachers might provide you with a packet of materials and activities that would let them practice skills that have been taught at school that day. This way, you'll be reinforcing things taught at school, and doing less "teaching" of new material. Also, think about fun ways to reinforce new skills that don't feel to the kids like homework. Labeling things that you are using to cook dinner, or counting pieces of spaghetti is infinitely more fun than what happens after you say: "OK kids, get out your (ugh!) homework. Keep the focus on home FUN!
Some families get more done at homework time when they set up an incentive program. Offering the children one minute of TV time (or better yet, story time) for every minute of productive homework might help them get on task and keep on task with fewer grumbles (or yawns). In terms of the independence, they may still need you to help them get through the work. If they do the same kind of work independently at school they may just be dragging their feet to keep you by their sides. (If they worked by themselves, would you disappear?) You might try just sitting in the same room, sitting a bit back from them while they do one problem, then two, etc., as time progresses. You can build this independence into the incentive plan. "You've just done this one with me. Then next one is just like it. If you finish it without asking me for help, you get one bonus minute of story time. I'll be right here with you. (This might be a time to quietly read to another child, or move over to check his independent work.)