I taught Nova using the lure with a treat method, and Kerri just liked to roll on her back as a puppy so I taught her by associating the word with the action when I caught her doing it. Unfortunately Copley does not like to roll around and was only confused by the treat method so I gave up! My dogs know lots of tricks, and Nova is trained with the clicker for tricks so we are up to, many, many behaviors with her at this point. With so many other options of thing to teach I just sort of gave up on the roll over with Copley.
If anyone has another method though- I am all ears!