The cheat you're looking for is
boolprop allow45degreeangleofrotation true/false, or if your game is picky about having the caps in the right place (mine's not),
boolProp allow45DegreeAngleOfRotation . Use the , and . keys to rotate the object.
Using
boolprop snapobjectstogrid false on while placing things at an angle is handy, so is having
moveobjects on. Again, if your game is fussy for caps, then it's
boolProp snapObjectsToGrid true/falseI recommend once you've placed your objects where you want, put snap ojbects back to true and moveobjects off, since both interfere with door and window placement

.