Automatic NPC spawning?

Before you yell at me for not searching, don’t. I searched with google, the google option on facepunch, and the facepunch search, with a bunch of different keywords, and I found nothing related to what I wanted. I’m making a zombie survival map, and it’s almost done, except for the zombies. How do I go about making a template NPC start an endless spawning spree via trigger?

[editline]07:06PM[/editline]

And, my searches took me to requests section, I just noticed that, so admin, feel free to move this to “mapping”.

Npc_maker, npc_template_maker, and/or point_template.