When we took Holly to puppy class there was a deaf collie/aussie mix puppy who was sharp as a tack. They used hand signals and it knew sit and down.
They just basically, did the command sign, lured it into the position and treated. That puppy was so cute though and you'd never know it was deaf because it responded so well to the sign language command and it knew that if it came and sat by your feet you would give it a treat.