Originally Posted by Altenweg
I don't necessarily disagree with CM, but I do have a different approach.
When he say's I hate you and you put him in time out you are giving him attention. Sometimes any attention is good attention, even if it isn't positive.
My son went through an "I hate you" stage, at first I gave him time outs and I also told him how much it hurt my feelings, it was like giving him a key to the city, he started saying it even more.
One day I decided to take a different route. When he said "I hate you" I said "that's to bad, because I still love you." and then left the room. He tried again and I repeated the same line, and then would go off to do something else. I acted as if his words had no effect on me. It wasn't instant but the frequency with which he said it quickly diminished and he stopped altogether within a week.
I don't know if it will work for you, but it's worth a try.
Good Luck.