Looking at your door top down, press N to bring up the window.
click the button on the lower left that shows the angle you want. They are in a square pattern, or just to the right of that is an Up or Down option.
enter the Key: Angle and the value in degrees. -1 is Up and -2 is Down if I recall correctly. The other values are 45, 90, etc. 90 is toward the top of the map I believe as you look down on it.