Hey! I'm not an animal behaviorist, but I do work for an animal shelter, and am around dogs about 24/7. Just because your dog ate two chicks, doesn't mean he's blood thirsty. It may take some time, but go outside with your dog on a leash, or harness with really YUMMY TREATS that your dog can't resist. Don't go near the coop, but just far enough so its within ear/eyeshot for your dog.
Each time you dog ignores the coop and looks at you or anything else... give him a treat. Do this over and over. Just keep "paying" him each time he ignores the coop. When you get comfortable, move a few steps closer. Repeat.
This may take time, and A LOT of patients. Keep your dog on a leash, and keep his attention on you (or his favorite toy) within ear/eye shot of the coop. Keep "paying" him with tasty treats each time he ignores the chickens.
If he goes crazy and bazurk, calmly walk away out of ear/eyeshot of the coop (no treats, no hitting, no choking, no ALPHA dog crap... just walk away until he calms down). Then camly walk back to where he can see the coop. When he chooses to ignore the coop, he gets rewarded.
Keep moving up, a few days at a time and practicing this. Like I said, it may take time and a lot of patients. I wouldn't let him out without a leash. Good Luck!