Our Dieter was the same way (although he was a rescue, we didn't raise him from a puppy). What I try to do is get him calm and relaxed on the floor with me, and even let him take a nap for a little bit. I'll just stroke him and talk to him and just let him think it's regular "snuggle time". I'll play with his feet a little, too. Of course, before I even call him to me, I've got the dremel close by, ready to go. After a while (could be a few minutes or a half hour, it just depends on how fast he relaxes), I'll pick up the dremel and turn it on. I'll maybe give him a few treats or praise him for staying, etc. Once I start trimming, there's no stopping. I try to do it as quickly as possible because if I take too long, he'll start pulling his feet away and fighting me.
It used to be that the second he saw the dremel he would leap up and run away. He's still very suspicious of it if he sees it, and it takes some coaxing to get him to come to me when that happens.
If all else fails, it might be worth the extra $$ to take your guy to the vet to have it done.
One thing that definitely helps us is the "settle" command. That keeps him lying down on his side (with his head down, too) and less apt to "leap up" and run away. Like anything, we had to repeat and repeat and repeat the "settle" training before he would do it reliably.
It takes a TON of patience to gain their trust on nail trimming (and ear cleaning with our boy, too). It took us about a year to get where we are now. Good luck, and keep trying!
