hi
have u read this
http://www.insanelymac.com/forum/index.php?showtopic=208410
After obtaining this information you should keep a file with the extension *. txt, then proceed on Mac OS X to edit another file system located in
/ System/Library/Displays/Overrides/DisplayVendorID-756e6b6e/DisplayProductID-717
to do this make a copy of it to the desk, and changed its name to DisplayProductID-717.plist, introducing the Raw Data obtained by the method described above, an example of the original file and the file already containing the Forced EDID Raw Data
first u must know what file is loaded for u display, mine is that..
then look for the picture and u will see
where u gonna insert u raw data
good hack