Requirements: Climb or Fly, though not strictly required you may want to be Flying to ensure you do not hit the Deathtrap
The ghost in San Francisco is only visible some of the time, this doesn't seem to follow any particular pattern of day or night.
So simply attempt a HUNT GHOST, if he is visible this will take you into the mine.
ASK GHOST HELP, ASK GHOST AVENGE and he will ask you to kill Coram and bring something to prove it.
Go and kill Coram, get the blackjack card (or some other card) from his corpse.
Return to the ghost, ASK GHOST EVIDENCE, GIVE CARD GHOST.
(note: I have had all manner of issues with this quest, the first time I killed Coram I gave him the card and it seemed to work, only it didn't,
I am thinking you need to do this in one session, do not rent, as this likely resets some quest flags)