I don't know much about this, cuz i never had a horse, but i'll give you practical advice.
Treat it lovingly, don't call it "breaking".
Call it gentling. When it does something good give it a couple sugar cubes or pieces of carrot or another treat. Be friendly, always touch it, make physical contact. Talk to it if you want it to know you and bond with you.
When the first part of gentling starts, don't let him know what's up, pet him and sweettalk
him. Keep petting him, but move all over his body and make sure you pet all of him and be careful on tickly spots. After petting, give him a treat. Always be friendly (duh).
If he makes a mistake, snap in front of his face and shout No! at the same time. This purpose is to scare him, not hurt him. Make sure he knows it's wrong. Good luck!