I would highly recommend getting a gamepad over just using the mouse fix. You can get a USB one for cheap enough.
The fact is the game was designed around the controller - the port was never originally planned so no thought was put into how well the controls would translate over to KB+M, so unfortunately there isn't much that can be done about that part of the problem.
I've heard that there are alternate key mappings that work better than the default that forgo using the mouse and put the camera controls on the keyboard - so you might try googling around for more information on that.
Other than that - I hate to say it but having a gamepad is really the ideal set up for Dark Souls. Its just the way the game was designed.
The fact is the game was designed around the controller - the port was never originally planned so no thought was put into how well the controls would translate over to KB+M, so unfortunately there isn't much that can be done about that part of the problem.
I've heard that there are alternate key mappings that work better than the default that forgo using the mouse and put the camera controls on the keyboard - so you might try googling around for more information on that.
Other than that - I hate to say it but having a gamepad is really the ideal set up for Dark Souls. Its just the way the game was designed.