many moons ago...there not too bad, definitely helps to do it in a warm inside area if possible and having an extra set of hands will help but basically you slide the old one off, slide the new one in place and begin to fill it with water. Once you've begun to fill it then you'll need to work out the wrinkles by hand as the water is filling. Once the water is an inch or two below the jet fittings then you'll need to find your openings, make a small cut with a utility knife, thread in the jet faces (don't forget your wall gasket) then continue to completely cut out the opening (very similar to how you would "cut in" a return fitting on a vinyl lined swimming pool if you have any experience with them)
basically the most difficult parts are getting the new liner to squeeze over the "shell" and making sure its not twisted otherwise you'll end up with some big wrinkles, then cutting in the jets also takes patience/experience
