Long time ago there was o nice discusion about this

anf this is some info i have:
'k Here's what I have so far.. [Fallout2.exe version is 1.02 US]
Everything is just a list- that is, everything is just [Data for elevator1][DataForElevator2], etc.
Buttons Count: 2ee1C (Fallout2.exe) 37ccc (mapper2.exe)
[00-03] # of buttons for each elevator
Elevator Image: 2ed5c (fallout2.exe) 37c0c (mapper2.exe)
[00-03] Base image to use (In \art\intrface\INTRFACE.LST)
[04-07] Button panel image overlay (In \art\intrface\INTRFACE.LST) (FFFF FFFF if none- that is, to use just the base image button panel)
Everything below has 4 entries per elevator- one for each possible button the elevator can have. The description is per button
Button Keys- 2f2fc (fallout2.exe) 381ac (mapper2.exe)
[00-00] Character to use for keyboard input for that button (00 if N/A)
Button Destinations:
Dest: 2ee7c (fallout2.exe) 37d2c (mapper2.exe)
Format:
[00-03] Target Map ID (0000 0000 if N/A)
[04-07] Target Elevation (0000 0000 if N/A)
[08-0B] Target Tile (FFFF FFFF if N/A)
Everything has been tested with two elevators (0 and 5), and all changes have produced the expected results. Haven't had any external (somebody other than me) tests yet, though.