I have painted the backs of a couple of chromed indicator housings with POR after sanding the chrome as well as I could to roughen it up. Although I haven't used them since, the paint did go on and stay on. It would probably work even better if they were sandblasted.
POR makes a product called Glisten PC which is supposedly designed to go over polished or chrome plated surfaces. I haven't tried it yet, but I have just bought some so I'll be trying it out in the next couple of weeks.
Painting the backs of chromed things like indicator housings is a good idea as chrome is not a particularly good corrosion inhibitor by itself. The painted indicator housings I have are generally in much better condition than the chromed ones.
Ain't nothin' like the wind in your hair.