Paper training and litter box training are quickly becoming popular among owners of smaller breeds of dog like the Chihuahua. You can use paper or puppy training pads, both will soak up urine and hold poop in place until you can clean it up. In many ways, training your pup to do his business inside in a specific spot is a lot like training him to go outside and you can always use the paper training as a way to work your pup up to doing his business outside if you prefer.
Keep in mind that paper training does not mean throwing down newspaper all over the house. If you do this, then your pup is going learn to do his business all over the house. Doing this will probably slow the training process down and may result in your pup never actually being properly house trained. You must train your pup to hold it until he is on his paper in the appropriate area, which means training under the same tight time schedule as you would if you were training him to go outside.
Paper training is best described as teaching your dog to do his business on your choice of media (newspaper, puppy pads, towels, etc.). But there is more to it than this, you must also teach him that he can only do this in one spot in your home. The main idea behind this training is to teach your pup where it is okay for him to go to the bathroom so that he will stop going where he shouldn't.
The good news is that Chihuahuas are very smart and easily trainable. The bad news is that because they are so small it is much harder to spot when they are squatting down or lifting a leg to pee. This means establishing a routine in which you take your pup to his "potty" plays a very important role in teaching him that this is the only place he is allowed to go potty.
You don’t really need a lot in the way of supplies, some old newspapers or maybe puppy training pads that scented to attract your dog. You may even want to buy a holder for the pads to help keep them in place. Be sure to have plenty of your pup's favorite treats on hand and be available to take him potty when he needs to go or when it is time. The rest of it is all about being patient and ready to work with your pup until he has mastered this skill. You may also want a crate or pen you can put your pup in when you can't watch him.