Nope, huge fail, absolutely no mention of a vcgt tag anywhere.
There is plenty of documentation for loading LUTs directly, but the truth is that widows XP does not support the vcgt tag (which is not actually an official ICC tag, but a manufacturer created tag).
Not to mention that because it's programmatically accessible, other apps including windows tend to clear out the LUT and load their own. Which is why every PC calibration app has a tray app that manages the LUT.
CalMAN Lead Developer