I got it to work. You need to have your sim marry someone s/he knows is rich, kill off the rich spouse, then keep the urn or tombstone around until the ghost appears. Let your golddigger (I keep wanting to say "grave digger," which I s'pose is kinda the same thing) interact with the ghost. When the living encounters the dead, you win! ^_^

And really, the only point to it is for completion purposes a la legacy challenge, I think. Or making a single family obscenely rich in a very short amount of time.