in Hammer Mapping
A lot of the older tutorials are gone now. But if you mess around with a func_train and some path_corners you can figure it out.
You won't be able to make a very complex elevator in GoldSrc no matter what, that's for sure. And especially not in multiplayer.
I built a 6-floor elevator with opening doors and buttons for all the floors, and call buttons in HL1 (no elevator-attached doors, though, of course). But it doesn't work in multiplayer. And it REALLY fails in CS.
It also required about 500 entities.