hi howdy, here's how youI do it:
first add you?re door and all that other s**t that you wish to have in you?re miserable little room.
Name you?re door something, like for example: NOSE
Add a respectable aaatrigger textured thingy in front of the door and set it to trigger_once.
Now youI have to set the "target" to youre door's name (NOSE)
and wola, a pathetic mall door thingy...
(I'm not crazy...)