Strictly Business is acquired when you visit Paradise Falls. Aside from bribing the person out front, completing this quest is the only way of getting inside the town. If you do bribe him, simply speak with him again and you can still get the quest. Make sure you do not tell him you don't like slavery or the town will turn hostile and the quest won't be available.
You will need to shoot four targets with the Mesmetron, then speak with them and convince them to put a collar on and go to Paradise Falls. If you can get each person alone, you can have this done without the town they live in freaking out on you. If you are seen, everyone will immediately turn hostile. The four people you need are:
Flak from Rivet City
Red from Big Town
Susan Lancaster from Tenpenny Tower
Arkansas from Minefield
You will receive negative karma everyone time you enslave someone and there is a big chance you will piss off entire towns doing this quest, so it is suggested you save just before doing the quest, then finish it and reload your previous save.
See Strictly Business for more specific info.