Indeed. The downside of this is that you can change rotation of only pre-placed buildings, this method will not work for building build while playing the map.
To do this, first place where your buildings are supposed to be in map. Then simply go to Object Editor, find that building and change "Stats - Is a building" to false. Then pick each building you have placed in your map and change their rotation. Once done, go back to object editor and change Stats - Is a building back to true.