Hi Stein, please try the attached script. Instructions for installing a plug-in command here. This particular one only has a .js file and no .htm since it does not show any UI.

Once you have installed it into MoI's commands folder, a new command named QuickRotate will then be available. You can then set up a shortcut key for it and inside the shortcut key also put any of x y z to control the axis used by that shortcut key, and an angle value. So for example to set up a shortcut key to rotate around the y axis by 45 degrees put this in the shortcut key:
QuickRotate y 45

Hope this helps!

- Michael