Measure very carefully. Mark and cut the hardboard into the right-sized panels face up if you're using a table saw or hand saw, and face down if you're using a portable circular saw. For ceilings lower than 8 feet cut the board to allow a 1/4-inch gap on the top and bottom. This allows for expansion. Prior to installation, line the boards up, mark them where they will join and cut where necessary to fit. Also, cut as needed for the hardboard to go around fixtures.
Install hardboard and tileboard over a solid backing such as plywood. Install cement board that has been fixed over a moisture barrier such as Tyvek or asphalt felt paper. Clean the backing and sand with coarse sandpaper if the board is too smooth. Remove any dust from the back of the hardboard. Apply adhesive in a zigzag pattern to the backing and spread it with a notched trowel. Push the board onto it, taking care that the edge of the panel lines up with the studs starting at an inside corner. Leave a 1/4-inch gap between panels. You might need to hammer a few nails around the edges to hold the board in place. Use a rubber mallet or padded wood block hammer. After 15 minutes, press the board onto the backing again.
Use matching colored 1-inch ringshank nails every 6 inches along the edges, and 8 inches apart onto the studs through the panel grooves, which are located every 16 inches, to meet standard stud distance specifications. Do not nail Tileboard.
Wait until the adhesive has set, then apply matching silicone caulk in all the gaps and around the shower base.