I don't know why they did it this way, but Microsoft has this little web-based cleartype tuner which you can only find by driving on down to Microsoft's website. It's on [link|http://www.microsoft.com/typography/ClearTypeInfo.mspx|this] page.
Of course, it can only do RGB and BGR, no other options. My bet is there's a reghack out there that will let you reconfigure it any which way you want.