Anyhow, here's the source code with a compiled progs.dat to go with it. Just drop it right into your "base" folder that was contained in your original zip. I've done the best I can to properly comment the code in there so you can hopefully follow what I've done. (Also, a lot of the comments are just me being ass, disregard those / delete them, etc.)
Features:
* Use impulse 13 to interact. (I'm assuming this is your normal use key anyway)
* NPC will turn to face the player who's interacting with it. (Yes other players can steal his attention.)
* If you turn to not face him, aren't visible to him, or are outside of a radius of 120 units, he will quit interacting with you. (or if you press 1.)
Cons:
You will need to modify him a bit if you want him to do stuff like HL Scientists / Barneys. (follow you, fight monsters, etc.) 'course, this should go without saying.
Enjoy!
