I have a bath fan on ceiling and a light on wall above mirror that work off the same switch. I would like to put in a fan/light combo(fan has two lights that will work off separate switches), but also would like to keep existing light on wall. I would like to control them by using the leviton three rocker switch. Is this possible? Can anyone explain how to wire this.

Electrical Supplies - Leviton - 003-1755-W Three Rocker Switches