Hey dude,
I was also trying to train my dog (chewie) to attack on command and doing more things like roll, play dead and such.
I tried all the tips I got from people, but most of them never worked..
The only thing I actually managed to train him is to sit and not pee in the house.
I did that by an advice from a friend, which told me that when ever the chewie is waking up,
I have to take him outside for a short walk, since after he wakes up he need to pee and poo :).
When I almost gave up on chewie, a friend came to me and sayd that he had the same problems with the dog ( like chewing the chairs and such things ),
He recommended me a book, that he told me he used to train he's own dog with.
The book name is
Secrets to dog Training and the Author of the book is
Daniel Stevens.
Now chewie behaves like a soldier and can perform all kind of tricks, which I never imagined he could ever do!
I'm proud to say that chewie is part of my family now...
Good Luck with your own dog,
Rephael.