Haha I like the MGS sounds for lab sounds. They are like, the perfect generic MIDI files you'd think to find in an old "looking through the lab" part of a game.
A few Ideas that hit me while reading your ideas lol:
Log-in sounds : The clicking keyboard and then boot sound you hear in a lot of old games when accessing a computer, if you don't know what I'm talking about let me know and I'll try to find something. I think Fallout three uses a somewhat "modernized" version of the sound OR The sound of the footsteps walking up and opening a door lol (that always was just an addition to the creepiness
Log-out : definitely some type of zombie groad, Possibly even the dying sounds from RE1
Or possibly a Nemesis moment (I was a huge Nemesis fan back in the day
)
And some things like the sound of unlocking doors and jangling keys here and there. All those little sounds that made the game as spooky as it is.
Just an opinion. I'm sure you will come up with some awesome stuff!