If you're using camera.sqs, there's a much simpler way of doing it. Go to your Controls options and select Bulldozer Controls from the drop down menu at the top of the window. Then modify the appropriate keys to use "Mouse Left", "Mouse Right", etc. Then you'll be able to control the direction of the camera with the mouse, and the movement with the keyboard. Or, you could even go one step further and map the movement controls to your joystick, giving you even more precise controls. Some people have done this in the past, with excellent results.
Hope that helps.