The retail snow leopard install disk will only install on a GPT formatted disk. That's why in my guide I have it install on an external GPT formatted drive and then copy it over to the MBR formatted internal drive.
But before you try that, you might want to just test if you can boot with [url="http://www.insanelymac.com/forum/topic/279450-why-insanelymac-does-not-support-tonymacx86/"]#####[/url] and get the installer running without a kernel panic. If it does, then it might be worth the effort with the rest of the guide.
Another way of installing on MBR is by restoring the installer disk to a usb drive or writeable sparsefile and modify the osinstall files to allow it to install to a MBR formatted drive. Search this site for osinstall and mbr for guides on how to do that.