easiest way for me would be
-restore the snow leopard DVD to a 8gb partition on the external usb
-install modUSB.pkg to this partition using your mac (careful not to select your macs partition during installation selection). modUSB makes the install DVD you restored hack compatible and will add necessary files automatically during installation*.
http://www.osx86.net/view/2073-nawcom_cd.html = modusb download location
-boot from this usb drive on your laptop and install mac OS as you would on a normal mac
*after installation some of your hardware may not have the right kexts (drivers). You will need to figure what hardware your laptop has ie, the gpu,wifi card, sound etc and see if there are existing kexts for them