So basicly, I tackled what I think is what you wanted. An elevator that goes up and down, only stopping at each floor automatically. The elevator can be called and then the player can get on and take you between levels.
The way it works is a tandem system where one object drives another object, periodically. That is,
sprite (A) moves every three second a given distance. Sprite (B) scrolls to it smoothly and stops. Repeat.
Sprite (B) is the elevator and so Sprite (A) is the motor. However, we have to take into account that the Elevator is always in one of three states: Up, Down, and Call, where call is the only state triggered by the player.
so, when the level loads, we set the initial state to Down. Which drives the motor to snap between floors. Once it makes it to the bottom most level, it changes to Up state. If the player "Calls" the elevator, the motor is instantly snapped to the floor that the player is on. Remember, the motor can snap anywhere, but the elevator will always smoothly scroll.
I've attached a capx with notes on it.
I also encourage anyone else to see if they can make it better. I feel that, although I got the end result, that it could be a bit tighter. But hey it works.