Since many of you have issues getting your AMD Radeon HD 6000 series card to work in Mountain Lion (when it worked great in Lion), I decided to make this guide.
Part 1: Setting up the UniBeast Drive
1. Insert your UniBeast Flash Drive into a working Mac. Maybe your MacBook Pro, working Lion installation, etc.
2. Run this command in terminal to unhide files "defaults write com.apple.finder AppleShowAllFiles 1" (copy and paste that into terminal and hit enter)
3. Force Finder to quit. You can do this in activity monitor. It will automatically restart.
4. Open Finder and navigate to your UniBeast Drive
5. Navigate to System/Library/Extensions
6. MAKE A BACKUP OF the kext "ATI6000Controller.kext" and then DELETE it.
Part 2: Booting from your UniBeast Drive
1. Boot from your UniBeast drive like you usually would. Use the command "GraphicsEnabler=No" in order to boot into Mountain Lion Installer
2. Install Mountain Lion as you usually would
3. After installation, bootup Mountain Lion by booting into your flash drive and then booting into ML, using the command "GraphicsEnabler=No"
4. Copy the ATI6000Controller.kext kext to your new desktop
5. Run KextBeast (Download: http://www.tonymacx86.com/downloads.php?do=cat&id=3)
Now your graphics should work. I have two monitors (Apple Cinema Display and another 25" 1080p monitor) running with full graphics acceleration Very fast and no lag!
For those wondering, I fixed my machine in my sig by replacing the parts with the exact same things. Not everything blew. I now run a surge protector on my phone line and computer.
Worked for me as well, thanks very much. Only problem I have because I use the Display Port if the org.chameleon.Boot.plist changes back to defaults after reboot Monitor does not sync, I have to login to computer remotely to restore the org.chameleon.Boot.plist file.