I managed to hex edit the disk pie chart colors in shell32 by getting a clue from Panda's link here:
http://vistastylebuilder.com/forum/index.php?topic=1304.msg6986#msg6986THIS IS ONLY FOR WINDOWS 7
Unfortunately things have changed since XP days. In 7 you have to read and enter the hex backwards as you can see in my code.
Worse is that I haven't been able to find unique locations for the colors of the Free and Used Space squares. The ones in the WinMatrix example don't work anymore.
Anyway here's how to change the colors:
Before
After
[Pie chart]
Original
00 00 FF 00 FF 00 FF 00 00 00 80 00 80 00 80 00
Replaced with
6E CE C2 00 FF CB 6E 00 B1 D0 4A 00 B1 D0 4A 00
[Free Space] Pink
Original
FF 00 FF
Replaced with
6E CB FF
[Used Space] Blue
Original
00 00 FF
Replaced with
C2 CE 6E
[Bevel] Purple
Original
80 00 80
Replaced with
4A D0 B1