Actually a good Yorkie mom begins the house breaking, she can smell the urine in the bladder and pushes her pup over to the pad. I wouldn't worry about training to go outside at this point, most Yorkie pups are with their mom's at this age. I would wait till she's 12 weeks before I start to crate train her and in the meantime I'd use more pee pads on the floor of her x-pen, basically most of the floor should be covered with pee pads so she can't make a mistake. You never want them to get use to their own urine, so change the dirty pads and pick up poop as soon as you notice it. I think this thread has some helpful tips.
http://www.yorkietalk.com/forums/gen...ebreaking.html