Actually, your dog may be able to hold his bladder long enough as long as you take him to poop/pee right before you leave, and right before you come back. The puppy is going to be four months, so they can hold their bladders for approximately 5 hours, maybe more, maybe less. If you're lucky enough, he won't have to poop or pee inside the house. To housebreak him, some dogs may already be housebroken, or they don't poop or pee at home unless they can't hold it any longer. That's like my dog. He knows he's not allowed to poop/pee in the house, and every time that we notice he has, he goes into his bed and just sits there quietly. If you find that your dog is not housebroken, simply every time you catch him in the act of pooping/peeing, NEVER punish him. This gets the puppy to be scared to get rid of his waste in front of you. Then he'll do it when you're not looking or something like that. If newspapers don't work, use puppy pads. These pads are formulated so that the dog WANTS to poop or pee on it. Slowly move the pad towards the door and eventually outside. By the time he is housebroken, he can hold his bladder long enough so that he won't have to poop or pee indoors. Also, 6 hours is a VERY long time for a PUPPY to be alone. To keep him occupied, maybe you could turn on the radio or TV or something so that he's not too lonely, or just make sure he has a bunch of toys. Hope I helped! :)
By the way, if puppy pads and newspaper don't work, I've heard of litter boxes for dogs. :D Give that a try maybe.
I have a chihuahua :)