Che's description of the lighting sounds about right, but I want to address another issue you brought up. You said:
use a 4 foot octobox, center at eye level with the model, 1.5 feet out from model's face at center, and 45 degrees off camera axis?
The only time the center of the softbox should be pointed at your sitter is when you are doing over-and-under lighting (or "clamshell" lighting) or Paramount lighting ("butterfly" lighting). If the softbox is off the camera axis and the center is pointed at your sitter, then half of the light is passing behind your sitter into empty space.
Instead, move the softbox so that the sitter is near the far edge. You don't have to move it far enough forward to be a "feathered" light; just don't waste all of that wonderful diffuser area lighting empty space (unless you really want to restrict the light for effect). And yes, "close enough" is a lot closer than most people think if you are really going for soft light -- you'd want to be right on the ragged edge of having the box in-frame a lot of the time. Once you're about twice the box's diagonal away from the subject, it's just another light -- you might as well be using an ordinary reflector for all the good the softbox is doing you.