Found this tool over at the CD Freaks forum:
http://club.cdfreaks.com/showthread.php?s=&threadid=91316

Let's you hack your firmware to do stuff like allow 8x burning for 4x media and 4x burning for 2x media. And it's customizable, so you can choose which media codes you want to modify. The author is also supposedly working on a graphical frontend if people are intimidated by the command-line interface.