Yep, as someone said below -- it should never take 2-3 hours at this age. He has begun to think that's what it always will take and his resistance will get worse because he dreads that long, drawn-out battle -- and the resistance will draw out the battle even more, as you know!
Don't wait until after dinner (not sure if that's when you have him do it now). A brief but essential break after school for a snack and drink is needed, but don't let him watch TV or start to play during that break time; get him to move to homework after just a 15 or 20 minute snack break. Maybe for now, instead of being right in the room with him, be nearby and have him tell you when he has finished page one; when he has finished page two, etc. so you know he's progressing. Figure out whether he really needs you to sit right with him or whether that makes him balky and resistant -- especially if he moves to homework quickly after coming home, he may do better if you are in the next room but he knows you're still paying attention to what he's doing with his homework. Are you checking answers for correctness or just ensuring he has it done and has followed the directions? If the former -- maybe stop that for a while at least and just be sure he does it (as long as he doesn't just put down random stuff to get the blanks filled in!)
If his quiet homework space is in his own bedroom (again, not sure if that's the case), and you think he will get distracted in there by his toys etc., make his quiet homework space in another, distraction-free space so you can leave him to it but know he's not getting pulled away by the stuff around him.
Just to get over this hump, you also could consider a reward chart for getting homework done -- not done perfectly, but getting it done to the best of his ability, within a certain time frame. Yes, homework is part of the child's "job" and shoudn't necessarily bring a "prize," other than knowledge. But for now, it might help him to see that if he completes all his pages for the week in X time without a fuss (and you should be clear with him exactly what constitutes a fuss), he gets to have an extra 30 minutes TV time or whatever really works for him. Don't go overboard of course -- I wouldn't promise a video game system or something huge for just doing homework -- and emphasize that getting it done is indeed his job, but it's a possibility.
Did you ask his teacher for tips? Teachers have seen and heard it all, and I"m sure the teacher has had other kids who are resistant and spend hours doing homework that should take 20 minutes. The teacher may have ideas you and I haven't thought of!
If you can make homework a necessary but brief thing now, and get him used to powering through it and just doing his best, rather than getting frustrated and letting it drag out, he will develop good study habits. It's good to do it now because by fourth grade (where my daughter is now) the homework and projects can really pick up!
You're doing well to have a special space already, and to parcel out the pages a few a day so he understands it's good to do a little as he goes along and not wait until the last minute. You'll get there!