The right way to do a racing harness is to have a roll cage, because that's where some of the belts mount. I wouldn't do it on a daily driver unless I was required to run them, I don't feel like climbing in and out of racing harnesses all the time.
Might want to check out the CG-lock device for around $40. It's a little gadget that slips on the tongue of the belt that allows you to "lock" the waist strap part so it won't move. That way you can tighten it up nicely to keep you in place during hard maneuvering.
Best part is you can take it on/off as desired. If you're not looking to go all the way with racing seats, a cage, etc., it might provide most of what you're seeking...
Schroth or Corbeau make harnesses that bolt to the stock locations. You can use the harnesses or stock belts for driving. Both are available in 3 or 4 point.