To install shower wall liners, coat the back of one panel, and attach it to the wall. Become familiar with the manufacturer's instructions before doing this, as you might have to remove the panel for some time after attaching it. Measure the dimensions of plumbing fixtures and the distances around them, and cut out holes in the panels to fit those measurements. Put the rest of the panels in place, attach the plumbing fixtures, and caulk all the seams.
Before starting the installation process, shut off the water at the valve, and disconnect all the plumbing fixtures. Examine the walls in the shower, and decide whether to remove the tiles. You can use many liners without removing the tiles, but consider whether you want to cover all the area in shower liners. Make sure to wear protective goggles when removing bathroom tiles, and smooth out the drywall before proceeding. If you don't plan on removing them, clean the tiles thoroughly to get rid of mildew and dirt.
Apply joint compound to the surface. Make marks on the walls where the liners are going to be, and use a 4-foot level for more accuracy. Hold the panels against the wall to make sure that you've measured and marked everything correctly. If some liners don't fit in completely because of the bath tub, cut them.