Jerry said, "
I'd say that installing a pull-down ladder in an existing 2x2 attic access opening is 'altering' that opening, which would then require the opening to meet the current minimum size of 22 inches by 30 inches..."

I'm not so sure that evey one would interpret the act of installing a ladder (without changing the opening size) as "altering" in the sense that it must be brought up to current code.

Is replacing the cover an act of altering? What about replacing the trim around the opening?

I just don't follow the logic of how installing a ladder in an existing opening (assuming the opening size wasn't changed) would require bringing it up to current code.
JF