At first I was giving my dog a lot of table scraps too. Then, one day, the little ah heck decided to stop eating dog food. So, I got pissed off and decided not to give her anything at all that day. The next day, she was happily eating dog food.
I've also trained her so that she has to sit before I put dog food down for her. And then, she waits until I say "eat". Also, she wont eat food from my hand, even if I stick it right in front of her. She's only allowed to eat it once I toss it to her. Basically, all I did was put food in my hand, and wave it in front of her face. Initially, she would go for it. I would take my hand away and tell her "NO!" After a while she got the picture.
That dog's a belgium malinois (sp?). My other dog was much harder to train though. She's a rottweiler, strong and stubborn as hell. When I was training her to heel, I had to literally pull her, with her feet dragging, across the backyard. But I think it all comes down to willpower. Once the dog realizes you're even more stubborn, then you're set.
dfi