What's the best way to blacken tail lights?

What's the best way to change these tail lights a href="http://www.cstatic-images.com/supersized/DMI/195619/692.07.jpg" rel="nofollow"http://www.cstatic-images.com/supersized…/a into these tail lights a href="http://carphotos.cardomain.com/ride_images/3/703/4841/26757420030_large.jpg?" rel="nofollow"http://carphotos.cardomain.com/ride_imag…/a