Hope someone can help.

I want to build a custom - tiled shower base in my basement (cement floor). The area already has the rough in for the shower. I have read the steps for building the base if you need to lay a sub floor i.e
Subfloor, tar paper,metal lath, floor mortar, laminating adhesive, membrane, thick bed mortar, metal lath, floor mortar, thin set then tile.

As my floor is cement, am I able to miss some of these steps (start straight from step 5 laminating adhesive) or is there another solution?

I'm also thinking of using the paint on membrane (from Home Depot) is this a good product and, if so, do I need to cover right up the shower walls or just the first 6" or so?

Thanks in advance
Al