Sorry for my absence, I was working on OSX Installer found in new Snow Leopard 10.6.3 Retail dvd, Build 10D575.
This patch enables you to install OSX Retail on an hard disk with MBR based partion scheme, thus allowing multiple booting with other Windows Operating Systems.
Like in the previous 10.6 version, you have to replace 2 files in the original dvd content:
-OSInstall goes into /System/Library/PrivateFrameworks/Install.framework/Frameworks/OSInstall.framework/Versions/A/
-OSInstall.mpkg goes into /System/Installation/Packages