I would use food as a reward for good behavior. If she turns her butt to you, smack the CRUD out of her! If she just flattens her ears, I would talk to her and "kiss" or "cluck" to get her to put them forward, then treat her for that. If she bars her teeth, then I'd make her back up out of your space, and then give her a treat when she stands calmly and puts her ears back forward again.
When you do get her out, do lots of "nice" things with her. Brush her, hand graze her, then put her up. If she likes baths, give her a good bath. If you're able to, hand walk her around the property or on some short "trails", letting her graze when she's being good. Show her that when people come to halter her, it's often a "good" thing.