Adding a pearl powder or paste to ss will take some test panels for the "right" amount. Won't have quite the pop as a tri coat or in the first coat of a clear type job. You'll likely notice the white being a bluish shade until the sun hits it and then you'll get some sparkle. The amount just depends on the effect your after and the more pearl you add,the flatter it will look. If the ss is a urethane,you could always clear it with the pearl in the first coat or use an inter coat clear/pearl for effect and then clear like a tri coat.
Pearl needs some "space" above the base to really work nice,reason for the inter coat or in the clear.Just using it in the base ,it has no "space" and kinda just is "there".