Hollow metal doors can be installed in about 15 minutes, assuming all the tools are on hand and you know the steps involved. Metal frames are installed during the framing of the walls. After the door frame is set, the studs around the door frame are cut and installed. The benefit of hollow metal door frames is their durability and how quickly they are installed. A major difference from that of wood jambs is that metal door frames are not plumbed until the drywall is installed.
Install three door clips on each of the legs. These clips come with the door frame and only fit in one way. Install one 12 inches from the bottom of the frame, one in the middle and one 12 inches from the top of the frame.
Set the door frame in the opening and attach a 2-foot magnetic level to the top of the frame. Shim one leg or the other with pieces of metal studs until the frame is level.
Drill two holes through each floor plate with a hammer drill using a 1/4-inch masonry bit and drive in two 1/4-inch-by-3/4-inch long drive pins. Drive pins are concrete anchors with a pin that is driven in with a hammer. Be careful to keep the door frame centered on the wall track while drilling. If the floors are wood, use 1/4-inch drywall screws to attach the plates to the floor. You may need washers if the holes are larger than the screw heads.
Slide the metal studs on each side of the door frame against the clips. Center the frame on the studs and clamp the studs to the upper clips, using locking C-clamps. Place two self-tapping screws into the clips.
Clamp the remaining clips to the studs and attach two 1/2-inch self-tapping screws into each door clip.