Both of my chins use litter boxes. My girl Sidney who we have had since she was 10 months old goes ONLY in her litter box no matter what. We just put her litter box in the corner she went in most time and put the litter box there. Now, we can move the litter box anywhere and she will ONLY go in the litter box.
My boy Fleury, we found him outside and I'm not sure how old he is but we are pretty sure hes older. We put a pan in the corner and he seemed to just pee in any corner so we put the litter pan in one corner, a chin chiller in another, his house in the other, and his hay in the last corner so he goes in his litter box to pee most of the time. Sometimes when I take the chinchiller out of his cage he will run to that corner and pee....I'm not sure why but he goes in it more than not.
Keep in mind, this is only for peeing....they poop EVERYWHERE and there is nothing you can do about that!