I have no experience with that particular stereo, or with a 3rd gen 4runner. There are some great how to-s on this site though. The best way to find them would be to do a forum search for "3rd gen 4runner stereo install"
I haven't read through that thread. When you order a stereo make sure you get the installation kit. I order pretty much all of my stuff from sonicelectronix.com because they include the installation kit and wiring adapter with every stereo they sell. They also have an amazing return policy.