well there is an easy way to do this
an led use 4.5 volts at 0.02 A amps of current so all you need to do is to put a resister in series with the positive (+) or neg. (-) side of the led that will brake down the 12 volts to 5 volts or less
a 300 ohm resistor could do the trick if you get any problems i am on msn:
use
justhurtz@yahoo.com (it works on msn also)