Very simple, use the patch to overwrite the mission_templates.txt in your native folder. Please backup your mission_templates.txt first.

Key up: raise the camera
Key down: lower the camera
Key left: zoom out
Key right: zoom in

When any arrow key is clicked, the manual mode will be enbled, no need to press any keys to toggle the mode. If the left Ctrl key is pressed, the movement of the camera will be five times more. Press R or `or left Shift to end the manual mode.