Here goes:
Pick up some thin backerboard, 7mm or so. And your new epdm or pvc shower pan/liner.
Figure out where your finished floor tile height will be and mark that on the walls. Now chop out the existing old adhesive/plaster in a 5-6 inch band from that point up, 7mm or more depth clearance all around(maybe less or more on the height off the finished floor, depends on local plumbing code). This will give place for the liner edges to go without screwing up your wall thickness...
Figure out your floor drain height - they're all adjustable but you need to be in the ball park or you'll screw yourself. Remember you'll need room for the initial sloped cement, then the pan, then the setting bed, then the thinset, then the tile...
Lay a bed of thinset, cement, what have you - sloping from the walls to your drain and in compliance with code (1/4 inch per foot or CH equivalent slope)
Install your new liner/pan.
Put up the backer board with some heavy duty construction adhesive - pl1 glue - liquid nails type stuff. Run it down over the edges of the liner/pan. Create a nice smooth surface and check your angles and measurements or you'll be creating some nightmares when it comes to set tile.
Tape your joints and corners like you would drywall - use thinset and fiberglass tape.
Trowel on a thin coat of rubberized liquid waterproofing membrane (Hydroment or some DE/CH equivalent, over everything (well, at least down to the bottom edge where the backer board meets the pan).
Follow all manufacturer's directions!
Now you're ready to tile (after laying/trowling down a sloped setting bed of min 25 mm thickness on the floor. You'll be laying your tile with thinset onto the setting bed...)
Make sure your floor perimeter is perfectly level, and the first row too...! Many pros will run the first row down to a point lower than the finished floor tile height (before doing the floor) This leaves you a nearly full tile width to hide joint lines that will inevitably want to converge on you because nothing is ever perfectly square. However, also calculate from the floor up to the ceiling and make sure you wont be left with a converging joint at the ceiling intersect point, adjusting accordingly.
Anothr trick is to start with the 2nd row of tile, set onto a thin ledger secured to your membrane coated backer board. This gives you something to hold the weight of the tile as it goes in, and prevent sagging. Lay the floor tile, then pull off the ledger and pop in the last (1st) row, cutting to fit... this saves tons of work on your floor tile cutting ('cause they're so tiny or are a pain in the ass to cut when glued together onto a mesh backing) and gives you a perfect joint..
Use a good quality grout - its worth the extra couple chuffs.
Anyway, plan it out well because you don't want to do all this twice!
Have fun!