I assume you've already removed the ECU from the car. If not, it's located above the glove compartment. It hides behind a decorative plastic cover held on by a "rubber band" that stretches across the top. After taking off the plastic cover, just remove the two bolts that hold the ECU up against the underside of the dash. Depress the clip that holds the cable connector onto the ECU and wiggle the connector off.

Once you have it out of the car, you'll see that the metal cover is held on by about 8 tabs. Just pry these tabs up and pull the metal cover off.

You will then see two boards stacked on top of each other. Pry the boards apart on the end that has two plastic posts between the boards -- each post will snap apart. Then at the other end, depress the plastic tabs that lock into the board from the under side, and wiggle the board back off the bracket that it sits on.

Open the two boards -- like you would a book -- and you will see the PROM chip. It's the only chip that sits in a socket instead of being soldered onto the board.

Count the pins, reassemble and install and you're back on the road.