The hub pattern might be right. You. however, can't use the smaller 14 inch Yaris wheel. They supplied the 15 inch on some Yaris models.
If you have the C with the steel wheels, then you can go to the junkyard and get any 15 inch 4 lug steel wheel, mostly off hondas and just throw it in your trunk and you will have a full size spare. Thats actually what I plan to do when I get new tires; buy a spare tire and that way I can have a full spare and do 5 tire rotations.