Designing Level Editor in Unity 3d using C# - repost

Need a level editor designed in unity 3d whereby the game objects can be assigned to a button on the level editor. The editor should also be able to write to alter the objects size by writing to an XML file, the objects read their size from the XML data and adjust their dimensions accordingly. I also need it to be able to view the XML file in the Level editor itself. I also need to be able to click a button to generate a new attribute tag in the XML file.