We are replacing a tub and the tiles around and above the tub. We are using hardiboard and spectralock adhesive. From what I have read, you put plastic sheeting from bottom of tub over tub flange, and then do you put the hardiboard from the tub flange up?
When replacing tiles do you start at bottom of tub and work up? Is ceiling last and is there special spacers that hold tile in place for the ceiling? Any special adhesive for ceiling tiles?

We do not use adhesive for tiles on Hardibacker, I use modified thinset followed with a epoxy stainproof grout. Tiles start at the tub and the ceiling is last. You must get a perfectly level chalk line on your first course. I make a story stick which is like a yard stick with the size of a tile and grout line marked. Holding this stick on the wall I can see if I can finish at the ceiling with afull tile or what. I generally make my first course and last course the same size if they can't be both full tiles.

You can put the plastic sheeting on the studs as a vapor barrier over unfaced insulation
Attach backer board with gal roofing nails
Lay out wall tile
Start with a level line at bottom of wall and check the tub for level
If the tub is out of level attach a ledger board staring with the second tile and go up
Then finish by removing the ledger board and fill in bottom cuts as needed:)

Just to add a bit on how James Hardy wants his Hardibacker installed. The board must be glued, I use the modified thinset, and then screwed with special green screws. Seams need to be taped with fiberglas tape or better and then mudded with thinset, then you are ready for your tile.