After you have gone through the work of gathering your three partners in this mess and gotten them all safely to the fountain, Elijah will tell you you have to redistribute them across the Town once more. Regardless of how annoying he is you must do as he says, so I suggest beginning with Dog. If you have a high intelligence, take God along; if not, take dog along. If you chose the former you must bring him two ghost meat in order to get him to follow you. Make your way through the Villa and Salida del Sol until you get to the row of switches. If you chose God, simply talk to him and he will agree to work them. If you brought Dog, you must lock him in to get him to stay. For a full, detailed walkthrough, check here.
Dean Domino should be next on your list, and you must bring him to Puesta del Sol. Make your way to the severed wiring, and there he will refuse to stay unles you convince him. You have two options: turn on the holographic security, or threaten to break his legs. The threat is much quicker, but if you can't / won't you'll have to find the two corresponding terminals. One is through the door directly next to Dean, follow its path until you find the terminal. For the other you must go back to the Cafe at the beginning of the area. Enter it, and exit it from the back second story exit. Then simply cross the rooftops to the terminal. For a full, detailed walkthough, check here.
Christine is the last and possibly longest quest if you don't have 60 Repair. Take her to Puesta del Sol and once there make your way to the Switch Station. Once inside you'll need to activate the power by repairing the fuse box. If you have 60 repair you can simply jury rig it. Without 60 repair you'll need to find the three fuses (one is in a toolbox in the station, one is in a toolbox on the highest roof in Puesta del Sol, and the last is located behind a Very Hard locked door near the service route; not the locked door can be bypassed). With the power restored you'll have to deal with turrets and shielded radios; there are terminals to deactivate both provided you have the science levels. Once you bring her back to the elevator, she will reveal she is claustrophobic. You may either receive the computer pass code from the named locker in the Ventilation control room or you may force her into the basement For a full, detailed walkthrough, check here.
Finally you must make your way to the bell tower. It is located in Salida del Sol and you will have to fight numerous ghost people along the way. Once there, start the event (and pick up the codes next to the controls) to pop the achievement. With the event started, make your way back to the fountain past many more ghost people. Back at the fountain go to the gate to finally enter the Casino For a full, detailed walkthrough, check here.