Well, you need to go to the Doodads' tab, Object Editor, find your doodad and go to Art - Maximum Roll Angle (degrees) and Art - Maximum Pitch Angle (degrees). Before you double click the fields, select one and Shift + Enter. This will enable the input of negative values, to rotate them the way you want. If you mean rotate them facing-wise, place them in the Editor and hold Ctrl while having the doodad(s) selected and left click to make them point at the direction you want. In order to face any direction, go to the doodad, Art - Fixed Rotation and type -1.