If the dog is showing aggression toward the cats you may not get them together. It took almost 6 months for me to get Kiya to accept a kitty last year. I just got another kitty and this one was accepted by all 3 of my dogs and was able to be free in the house in a week. Crate the dog when the cats are loose. Work on obedience because "leave it" and a long down/stay are your best bet.
It also helps when the cats are dog savy. When I let the dogs in the house I yell out "dogs" and I am teaching this new kitty up high is safe. Even though my dogs are good with him he's still so tiny one paw swipe could be it.
Apache - Shiloh Shepherd 12/15/02
Kiya - Shiloh Shepherd 5/15/04
Lakota - WGSD 1/13/10