I posted this question on the Fpsbanana forum and this was one idea i got back,
from Brainz: "You could add two spawners, one at the top and one at the bottom.
When the elevator is at the bottom, the top one is disabled, when the elevator is at the top, the bottom one is disabled, when the elevator moves, both are disabled."
What would be the proper I/O to do that?
from fibbs: "Use an env_entity_spawner and set the template to the point_template you're trying to parent. env_entity_spawner is pretty much idetical to point_template except that it has things for auto-spawning."