Buick 1994 Century Owner's Manual page 54

You'll need a safety locking clip to properly secure a
child restraint in this position. You can get a locking clip
where child restraints are sold, or from your Buick
dealer (GM Part Number 94844571). The locking clip
must be the same as the one shown here.
Until you have this clip, secure a child restraint only in a
seat that has a separate lap belt (and a way to anchor a top
strap, if the child restraint has one). See the following
section about securing a child restraint in a center position.
Once you have the clip, follow these instructions:
1. Put the restraint on the seat. Follow the instructions
for the child restraint.
2. Secure
the child in the child restraint as the
instructions say.
3. Pick up the latch plate, and run
the lap and shoulder
portions of the vehicle's safety belt through or
around the restraint. The child restraint instructions
will show
you
how. Tilt the latch plate to adjust the
belt if needed.
If the shoulder belt goes in front of the child's face or
neck, put it behind the child restraint.
4. Buckle the belt. Make sure the release button is
positioned so you would be able to unbuckle the
safety belt quickly if you ever had to.
5. Then thread both the lap and shoulder belt portions
through the locking clip.