Remove the contents of your drawer, and remove the drawer from the cabinet or dresser.
Measure and mark the center of your drawer along the top edge. Mark where the center point of the lock will be. Make sure your measurement is in a place where the lock bolt will be able to extend beyond the top edge of the drawer and catch the upper edge on the surrounding facing of the cabinet or dresser.
Drill a hole that matches the circumference of the shaft of the lock using an expanding drill bit or a keyhole saw.
Sand the interior edges of the hole with sandpaper.
Remove the lock bolt and O-ring from the back of the lock shaft.
Insert the lock into the hole from the front. Position the key slot in a vertical position.
Replace the O-ring. Hold the front of the lock and press the O-ring against the backside of the drawer. Screw in the setting screws through the holes in O-ring to secure the lock.
Replace the lock bolt.