There are Hid fog lights that would fit in the stock location but they are very expensive. Yellowandbluelighting.com sells a fog light kit made for our 4runners and it comes with everything you need to install it. You could just put some hids in there and call it a day
Toyota 4Runner SR5 Micro DE Fog Lamp Kit 74560 - Micro DE - Performance Lighting
Heres a link on how to install hids in the fogs. I ordered this same kit and followed these directions and everything came out fine.
http://www.toyota-4runner.org/3rd-gen-t4rs/45655-hella-micro-des-hid-kit-plug-play-install.html