http://sketchucation.com/resources/tutorials/37-beginner/108-installing-sketchup-pluginshttp://sketchucation.com/resources/tutorials/37-beginner/108-installing-sketchup-plugins
手動で行う場合は
C:\Users\(ユーザー)\AppData\Roaming\SketchUp\SketchUp 201x\SketchUp\Plugins の 中にぶち込む