This achievement is unlocked in Episode 1: The Intruder in Scenario #5 - Nedry's Clearing. Select the episode to begin (if you've unlocked it).
The scenario starts off with you climbing the hill and opening the door to the jeep with a dinosaur jumping out. As the scene progresses you'll wind up on the road to track Nedry's foot prints.
Click LT and select up to go back to the jeep.
At the Jeep select RB to toggle the lights on top of the jeep
Use the right thumbstick and move it to the left causing the lights to move to the right and illuminate the tunnel (you'll see a tail disappear into it)
Click RB to leave the light moving scene (leaving the lights to illuminate the tunnel still)
Click LT and select the left scene, the one with the tunnel
Once your character has walked there, hold X as she scans the area and spots the badge
Blip!