Video
I purpously didn't put nodraw texture on elements that should finally be invisable, so you can see what is happening.
At the white wall:
A horizontal slider setup with a "mover_elevator", to control horizontal motion. From the button on the pillar, you trigger a trigger_sequencer, to have the slider go to the next stop. It has a "set frobable" function to ensure each stage is completed before all is triggerd again. The red blocks on the wall are the actual elevator buttons. When you frob one, the slider will go to that position. This wil f*ck up the working for the butto