Set the blade on your table saw to a 45-degree angle.
Cut an 8-foot-long two-by-four on a 45-degree angle down the middle to create two wedge-shaped strips.
Position the strip where the wall meets the ceiling. Have a helper hold one end while you hold the other. Two step ladders will be required.
Check the crown molding for a good fit over the angled strip. The crown must be flush at the ceiling and the wall. Trim any excess from the strip if necessary, using the saw until the crown molding fits correctly.
Cut as many 8-foot sections of two-by-fours as needed for your project.
Reset the table saw blade to 90 degrees.
Cross-cut each of the angled wood strips into 8-inch blocks using the table saw.
Fasten the blocks to the metal studs every 16 to18 inches around the room, using a power screwdriver and 3-inch self-tapping metal screws. Make sure that there is one block where every seam will be in the crown molding.
Mark a spot on the wall where the blocks are located, just below where the crown molding will be mounted, using a marker.
Secure the crown molding to the wood blocks using a hammer and finishing nails. Drive the nails through the molding, leaving approximately 1/8 inch of the head exposed. Drive the remainder into the crown using the appropriate size nail-setting punch matched to the head of the finishing nail.