Freestanding bathtubs are also known as soakers or if modeled after older tubs, clawfoot tubs. They are easier to install than between the wall tubs, and as their name implies, designed for soaking away life's little stresses.
Attach the feet
Place something, such as a heavy wooden box or a strong tool box, that will support the weight of the bath. Cover the box with something that will not scratch the surface of the bath. If you have packing material that came with the bath, this will work. Place the bath on the box, thus raising it high enough to work underneath.
Note the position of each foot. They are not interchangeable because the bath was leveled at the factory.
Install the two feet on the end of the bath that has the drain. It will require two people to attach each foot, one for holding the bolt and one for appropriately centering the foot over the attaching bolt while not scratching the bath or forcing the threads.
Install the two feet on the bath's end opposite the drain.
Remove the supporting structure, allowing the bath to settle on its feet. If the bath wobbles, adjust by adding or subtracting space washers in the wobbly legs. Since the bath was level in the factory, wobbling is probably due to variations in bathroom floors.
Place the bath
Mark out a place where you want to put the bath.
Mix up enough mortar to level the bath.
Apply this mortar to the floor and then lay a piece of polyethylene over the mortar.
Rock the bath into a stable position. Be sure to use a level, shims and the mortar. Shims should be placed over floor joists. Complete the bath's skirt.
Attach the corner supports to the end of the bath skirt that need not be removed.
Measure, cut and glue on the skirt. If there is another side that will be permanently in place, repeat the process. The corners that have been abutted together should be covered with outside corner trim.
Stiffen the part of the apron that is to be the access panel by gluing a piece of 2.5 x 2.5 cm (1 x 1 inch) fur stripping along its bottom on the side that will face the bath. Repeat the process at the top. Glue vertical supports of 2.5 x 2.5 cm (1 x 1 inch) spaced 45 cm (18 inches) apart. The access panel may be affixed to the bath side with industrial Velcro stripping.
The exact way feet attach to baths may vary somewhat between models. Check the manufacturer's specifications and instructions carefully. There are a number of freestanding baths that require no skirts. Explore all options. The number of companies manufacturing freestanding baths has increased significantly over the past ten years.
Do not attempt to complete installation without an assistant. There are also traditional clawfoot baths made of cast iron that should only be installed by a professional plumber. Do a thorough evaluation of the floor joists to assure that the weight of the bath will be readily supported.