Unfortunately, that doesn’t work for me. The Windows folder (in the root of the C drive) has no customize tab.
Editing desktop.ini within the Windows folder does not work, either. It is the same in Windows XP, but somehow IconTweaker is able to change the Windows folder icon all the same. I assume that the method IconTweaker uses, whatever it is, would work in Windows 7, also. I wonder what it could be.