Here are the steps to install a shower pan liner:

1. Install drain base: Place your drain base into a pre-made hole and screw the flange to the subfloor. If your drain is pre-assembled, loosen the bolts connecting the clamping ring to the flange and remove the clamping ring, but leave the drain plug in place in the middle of the drain.

2. Prepare slope: Create a slope for your shower pan by using a mixture of sand and cement. The slope should be 1/4 inch per foot towards the drain.

3. Measure scrap pan liner for curb: Measure and cut a scrap piece of pan liner to fit over the curb.

4. Measure and cut pan liner: Measure and cut your pan liner so that it covers your shower floor and extends up the walls by at least 3 inches .

5. Install pan liner: Fold the pan liner halfway over to expose the drain base and apply silicone caulk around the surface of the inner flange. Fold the liner back over, push the bolts through the X shapes in the liner and screw the clamping ring down over the four bolts. Finally, tighten the bolts until the ring has a snug fit against the liner.

6. Assemble drain base: Assemble your drain base by attaching it to your drain pipe.

7. Fold corners and secure pan liner to rough framing: Fold corners of your pan liner up onto walls and secure it with staples or nails.

8. Adhere pan liner to curb: Adhere your pan liner to curb using silicone caulk.