Lexus GS 450h 2008 Owner's Manual page 120

1-8. Safety information
Installing child restraints using a seat belt (child restraint lock function belt)
Rear-facing  Infant seat/convertible seat
■
STEP 1
STEP 2
STEP 3
118
Place the child restraint system on
the rear seat facing the rear of the
vehicle.
Run the seat belt through the child
restraint system and insert the
plate into the buckle. Make sure
that the belt is not twisted.
Fully extend the shoulder belt and
then allow it to retract slightly in
order to activate the ALR lock
mode.
Lock mode allows the seat belt to
retract only.