I've been using the drop in wedding cake steps for several years--ones with 2 rails.

Putting them in:
1) I have a sheet of 45mil poly that goes under them. This is available from Home Depot as the sealer plumbers put under showers. I put it down to protect the liner from any movement by the steps. I cut it bigger than the steps, but rounded. It's super-smooth so it doesn't abrade the liner.
2) the steps go in. I drilled holes in the leading edge of each step to help air get out. I use 3 50#bags of filter sand--I had the giant zip-locks and I put a bag in each of them. I get INTO the pool and lower them down.
1a) Don a wetsuit--best $100 I spent on the pool.
3) Put bags inside steps and maneuver the steps into position.
4) Install rails

Removing them...
1) Don wetsuit...FIRST!(I close Oct 1)
2) detach rails.
3) Remove sand bags, lift to deck, well out of the way.
4) Gently lift steps so air gets in and floats them.
5)get one edge of steps on deck, lift slowly to get water out, then lift it completely on deck.
6) Getting them out of the pool and to the shed is tough. I can manage it myself, but if my son can help (and he does) it's better.