NPC spawner script

I would like somoene to create a scrip who consists of spawning npc's (ally or enemy) Like the delta Squad from spec ops or the random generated soldiers from the campaign.
Is already any script like this done? Please tell me if you know or anyon wants to do it!
Thanks!

This likely doesn't answer the question and the video is about MW2 but this should AT LEAST point anyone who stumbles across this post in the right direction