Making a kid wear a diaper for not obeying you doesn't seem like it would work at all.
What would making a kid wear a diaper and using the diaper instead of the toilet accomplish when trying to get your child to obey you?
What you need to do is put the kid in timeout or give the kid a spanking when they just won't obey you or ground the kid to his or her room and take things away from them such as toys, video games, TV etc.