I have an overhead light wired with a single-pole dimmer switch on one side of the room and a 3-way non-dimmer switch on the other. I would like to add a third switch to this circuit if it's possible without losing the ability to dim the light. Is this possible? Also, the wiring diagrams I've found online all have the power going into the first (3-way) switch. In my situation the power enters at the ceiling fixture. What do I need to do differently for this?