Too long and too many pics to explain step by step but the full factory repair manual can be found here with the instructions with pictures......It's under EXTERIOR/LIGHTING/ SIDE TURN SIGNAL LIGHT ASSEMBLY/REMOVAL
http://www.toyota-4runner.org/5th-gen-t4rs/92594-modifications-write-ups-quick-links-faqs.html
4th one down by Super Nashman!
It's kind of a pain as you have to take the mirror completely apart as the screws that hold the lens on are behind the mirror and actuator and probably easier to just tape it off?