If it is for infrequent access, I would say to just cut a hole in the ceiling inside a closet, don't bother with the drop-down stairs. Cut a square hole between two joists, frame it with 1x's, and make a plywood square that is held up by the 1x's and stays in place by gravity. Add a piece of insulation on top of the plywood. Just make sure you cut the hole in a place where there is enough headroom to get into the attic once you crawl through your access hole.
My sister's house has this type of attic access, and when a tornado came through a few years back, there was no damage to the house other than the trap door that was held in place by gravity had been sucked up, and then dropped back down through the hole.
Ken