Hi,
Its sounds like you are on the right track. This is something that will take a lot of time and patience. Something you can try to get them more used to each other is to first work with the dog teaching it a few simple obedience commands such as sit, down, wait, etc. Once the dog knows a couple then put him/her on a leash in the same room as the cat, and work on the obedience commands. You will obviously need really good treats while you are doing this to keep the dog's attention. If the cat wants to come investigate she can. The important part is to keep the dog's attention on you rather than the cat. You can gradually work on doing this closer to the cat. You will probably always need to keep your gates on hand. Depending on the dog and cat you may never be able to leave them together when you aren't at home. Here is a link to a page that goes into more detail on how to work on getting dogs and cats to live together well, scroll down to find the appropriate section:
http://www.hsus.org/pets/pet_care/our_pets_for_life_program/cat_behavior_tip_sheets/introducing_pets_to_a_new_cat.html
For the cat's benefit you might want to try a product called Feliway. It comes in a plug in diffuser, consists of calming pheromones, and works well for any stressful situation. Most pet stores carry Feliway or it can be purchased on-line.
If you have further questions let me know. If this answer is helpful please click accept. Thank you and good luck!
Lynn
Veterinary Assistant
worked at a vet clinic for 15 yrs, BA in biology, have had cats most of my life