I have a SONY VAIO VGN-FS640w, and I solved the problem by creating a "hibernating monitor" - two resistors between 1-5 and 2-12. Plug this device to notebook when Installer is loading, the scren must blink two times, and then blue screen appears, at tis moment you should connect external monitor and see installer window on it, you can drag installer to main monitor, or continue installation on external monitor. When you finish installation process, and computer goes to reboot, connect "hibernating monitor" to computer and boot to Mac OS, screen will blink two times and you will see gray screen and hear music, connect external monitor, go to System Preferences>Displays and drag white bar to the notebook screen, then connect "hibernating monitor" and reboot! Enjoy! And don't forget to keep "hibernating monitor" plugged in!
P.S. Sorry for my ugly english, i am from Russia!