At the store I worked at, employees were allowed to install them, but not required to. We didnt get any special training on some magical way to do it so that it's guaranteed perfect, so I was one of the employees that wouldn't put them on for customers. There was usually someone else I could find that would do it though. Watching my co-workers, everyone had a different way, and none of them were totally perfect every time, so I just stayed away from the whole mess. Lol