Curisosity really?

I've always wondered how you housebreak a Chihuahua. Can you, considering how tiny they are? Can it hold it all night? Do you paper train it first? The smallest dog I ever had was a Beagle growing up. My mom paper trained her first then took the papers away when she was older. I can't recall her ever going in the house though. So what do you do with your Chi if you have one?