Different room, 90 days with a clean health/fecal check, diligent care to hand-washing and sterilizing, and nothing shared between cages. Even after quarantine, I don't put uneaten rodents in with a different snake, nor switch around hides or water bowls, and I wash or use hand sanitizer in between cages when cleaning or handling animals.

I do quarantine animals from a single source in a group (IE, a shipment from breeder X will have all the animals put in one room, while all the animals from breeder Y go in another).

It's not an ideal quarantine setup, but like most people, I can't afford outbuildings with seperate ventilation systems just yet.