If a slab, you can keep your existing drain if you build your own shower stall.
Out of treated wood, I would build the shower stall like you would a closet. Build the walls 16 OC, and on one side which is the open side you need to build a dam or small wall that the shower door sits on. The dam is usually about 5 or 6 inches tall. Depending on the type of shower door you will use, the dam must conform to the width of the door. Again, the dam would be built with treated wood.
I like treated wood in a shower area just in case of leaks and eventually it will.
Your pipe and handle area will be the same wall area and nothing will change there.
Now, the second thing is to install the cementious backer board, but under that you install the heavy duty thick plastic membrane that covers the flooring area and up the walls on all sides about three to four feet. This is one of your defenses against water leaking.
This membrane is stapled on the studs but not bunched up as the cement board goes over this.
Now, the floor area is the tough part. This is where you have the slab showing, the drain pipe up, and now you have the membrand on the floor area heavily caulked aroudn the pipe area.
The cement board does not go all the way to the floor area because the floor area is poured with mortar. The mortar is designed like the inside of a bowl so that all the water goes to the drain. It is not flat and is bowl shaped.
This has to cure properly and smoothly because your ceramic tile will adhere to this.
Once the cement is poured and the cement board is attached all the way up on all sides, then you begin hanging tile. Tile it in, Install the door and walla.
This is one big job and not a usual do it yourselfer job unless you feel good about this.