NPC Spawn was a simple ClientFX edit. Not all that hard
lately its been all about cracking attributes because we know the encryption method, and possible pass phrases, we just need modding bypasses
for Model mods, you need a bypass as well.
check the Rez Cham Bypass tutorial in the tutorial section. That's where you start. I'm bypassing for modding in a different way than is posted there, but thats a base start