i think that crating is a very necessary concept for any dog to understand, especially boxers. they have a lot of energy, and if not stimulated enough, they will get into trouble. don't give up on crating, even if your dog seems to hate it. i would bet that winston was one of the worst cases in history of trying to crate train. every time i'd put him in there for more than 30 mins, he would poop all over the place. it took him several weeks to get used to it. obviously, they would much rather be out running around, but i can think of many situations that a crate is absolutely essential. do a search on this site using the words "crate train"...you will get tons of helpful tips. and yes, as long as your puppy can wait to go potty for 3 hours, there is no problem with crating for that period of time.
please don't give up on crate training.
jim