Hi, I'm building a Dell Latitude D630 using Mountain Lion and SSD. I ran into the same problem of the Boot0:GPT error.
I tried your fix and was able to unmount the disk0s2 but I couldn't apply the fix, it came back with
dd: if=/usr/standalone/i386/boot1h of=/dev/rdisk0s2 unknown command
Am I typing the command in wrong, or is my Dell not compatable with my Samsung SSD?
Everything else appears to work when I boot of the USB key.
Regards, Ken.