I've been meaning to address your question, but haven't had a chance to fire up the game.
So what you're describing, in a real-world situation, is aiming your gun and maintaining that position, while allowing your eyes/head to turn and look elsewhere? Sounds like it creates an on-rails situation that disconnects footwork from the camera, where you can walk in a straight line (your aim locked) and look around without deviating from your line, rather than causing steering that's directly determined by your camera. This isn't possible on my scheme becuz mine assumes your aim and your "eye sight" are always tied together, for gaming purposes (while the real-world allows you to have a relaxed stance and not be in 100% aiming mode the entire time you hold the weapon).
You might achieve something close to that in Conduit by locking your camera (freezes your "forward" walking direction) and using a high Horizontal/Vertical View value to allow the camera to turn before your cursor exits the Bounding Box. Of course, there's still no way to lock your cursor's position. And when you release your lock, the camera will re-center to the current cursor position.

OH, YOU SEXY BEAST, YOU