This way may seem like a fluffier way to deal with the situation but it may help if nothing else does. I like working with two extremes of reward and discouragement.
This only works if your dog is food motivated though. I would leash your dog (this is big, the more the dog can get 'away' from you to the cat the dog wins), have a high quality treat (hot dog?) and sit in the room with a cat, when ever your dog isn't whining, staring at the cat or relaxes give a "Good" command and reward. You try and reinforce the good behavior. Every time the dog looks at you instead of the cat, reward. If the cat moves and the dog doesn't focus on the cat reward. The cat runs and the dog doesn't chase, reward. This takes time but then the dog gets more intent on looking for reward when the cat is nearby then actually chasing the cat.
If the dog lunges towards the cat I would make a loud correction noise then do what ever it took to flip the dog onto its side/back and not let it up until given the release signal.
Teach him the "look" command, where when you tell him to look he's supposed to focus all his attention on you. My obedience class was actually learning this when my dog was killed, but I digress. Preferably do this training in an area where the cats cannot create a distraction. Doesn't matter if the dog is food or toy motivated, whatever he likes use it to your advantage. Basically you get his attention with his reward and bring it up to your eye level so his eyes follow it. As soon as he looks you in the eye, praise and reward. As you progress, draw out the eye contact little by little and add the word command. Then when he starts getting it you can move on to training it in situations with small distractions and work up to the cats.
Our Husky loves chasing the cats...and he thinks it's all a game when they try to swat at him, but he's just too twitchy and quick for them. I've thought of holding him down while they go at him XD That'd teach the little sucker. Thankfully he hasn't hurt them. I'd do something about it, but he belongs to my brother and I have no say in his training (though if he does get truly aggressive and hurts/kills my cat I will take action, even if it means having him destroyed).