Overwrite NPC Defaults?

When making an npc, I want to have barney animations, sounds, etc. with a different model, but everytime I try this I get the default barney model.
Also, I want to do this kind of thing with the scanners, but they do the same thing.
Last but not least, is there a way to make a new rollermine so I can change with the rolling model and attacking model?
fyi, I don’t want replacements, I want to make stand alones.

The only think I can think of is to make an SNPC which is scripted to do the same thing as the normal NPC, but changing the model manually for each “event”

I sorta don’t have any clue how to script.
Isn’t there some kind of lua command to copy the npc script, and then modify it with the lua script without touching the original file?