So, a couple of issues here - do you expect your dog to live and work full-time outside or be a family companion that comes and goes frequently in the house?
If your dog is going to be a full-time outside guardian, he should live outside from the very beginning. Bringing him into the house as a pup will lead him to bond to you and the house more than the barn and the pasture and his stock. He may constantly come up to the house or try to get to the house. It also seems bit cruel to keep him in the house and then suddenly expect him to live outside. All LGD pups over the age of 10 weeks are fully capable of living outside in a warm, dry shelter or a stall in the barn. If it's super cold and he's coming from an inside environment, he may need a heat lamp for a while - although I'd still make sure he has the option of getting away from direct heat. These breeds lived and worked in the mountains, high pastures, and steppes for centuries and are perfectly suited to heat and cold with shelter. Give him lots of attention and affection out in his work space and he will bond to you as well as his stock.
If you plan on your pup only visiting the house occasionally I would still raise him outside during his puppyhood. Adult LGDs who make visits to the house generally do not have any problems with housebreaking. They are not comfortable using the house for elimination. An intact male may have a problem with marking, but intact males try to mark lots of things and need correction. Same thing with visits to the vet, etc. I've never crate trained an LGD and I've never had them eliminate in the house or vet office or even when taken someplace else.
If you are raising your LGD to be a family and home companion, you might need to crate train. If so, I'd follow the standard advice for any breed of dog. I've never done it so I'm not much help. Sorry
Remember, if you need predator protection, keeping your dog in the house won't help. He can't protect stock when he's inside.
