A resistor devider used to drop 12v to 4.5v would be inefficient and offset any power savings the LED had. (i.e, all the current that goes through the resistor gets turned into heat). Better option is to recalc the current limiter resistor for the LED being used. (only one resistor)
I'd run bulbs in series, or get 12v LEDS (which often have multiple LEDs in series). A solid-state regulator to drop voltage would be too much $$$ to be worth it when you can buy 12v leds.
On the original thread, I don't like LED interior light. The color is wierd for me. But I'll never use anything but for the tail, running, etc lights.