Remove the old latch, if necessary, by unscrewing its attachment screws with either a drill or a screwdriver. Take off all components from the door, including the handle and latch from each side of the door, as well as the frame part of the latch.
Position the new latch in the desired location. Mark the locations of the attachment screw holes and line them up with the old ones, if possible, to make installation easier. Drill through each marked hole with a metal-specific drill bit when drilling through metal doors.
Set the latch in place and insert the installation screws or bolts through the drilled holes. Tighten the screws or bolts in place on both sides of the door.
Position the frame portion of the latch on the frame in a location where the door latch will catch it perfectly. Have an assistant open and close the door while you hold the frame latch in place to make sure the location is optimal. Adjust the frame latch, as necessary, to find the right position then mark the location of the frame latch attachment holes.
Drill out each of the frame latch attachment holes with a wood or metal drill bit as determined by the frame material. Set the frame latch in position and attach it with the included screws. Test the door to make sure that it works properly.