[Trixter]

I don't know if this will help in your case, but I watched " It's Me or The Dog" and she dealt with a dog who would not leave the cat alone by working on the "Leave it" command. She taught the command first the way it is usually instructed with treats - Having the dog leave the food or object and then rewarding with food and praise.
When the dog had perfected the command, she continued by putting the cat (and Owner) on the bed in the same room, and when the dog approached, she said " Leave it " and rewarded with the treat and praise. It worked! Eventually the cat and dog could stay in the room with just the command. I hope this works for you. Good Luck!