In the buyDebug menu, you will find a sub-menu containing all the spawners, which you can place in your lot and will spawn whatever it was they should spawn on a regular basis. Treasure-spawners are among the ordinary treasure/tomb stuff and you can define their treasure by control-clicking on them with testingcheatsenabled true.
Be careful about placing spawners in community lots, I'm not certain, but I think if I've understood everything correctly that it creates some white boxes-thingies that obstructs the area.