How do I install the Graco Nautilus 65 LX for forward-facing use with a vehicle seat belt?

For forward-facing installation using a vehicle seat belt, place the car seat forward-facing in the back seat of the vehicle. Route and lock the vehicle's lap/shoulder seat belt through the proper belt path and tighten it firmly. Ensure that the seat moves no more than 1 inch (2.5 cm) at the belt path. The harness straps must be at or just above the child’s shoulders, and chest clip should be positioned at armpit level. Review section 3-C of the manual for detailed steps.