That's bad, since I thought that my inability to boot the installer comes from wrong BIOS settings

Anyway, I would change a little bit in your tutorial - if you don't want to mess with all the bootloader and BCD stuff do it like this:
Before installing OS X, use Windows to create an empty partition. Then run "diskpart" from command line and enter "SELECT DISK 0" (or whichever you are gonna have both Windows and OS X on) , then "SELECT PARTITION X" (X - number of created partition, where you want to install OS X), and then "ACTIVE"
Then install (Snow) Leopard from DVD, as normal. This will make Chameleon install on OS X's partition instead of erasing Windows' partition bootloader. After that you will be able to boot both Windows and OS X with Chameleon, without any further changes.

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AMD Phenom II x4 810 2.6GHz | Gigabyte GA-MA790XT-UD4P | Gainward GeForce 9800GT 1GB | 6 GB 1333MHz DDR3 RAM | 1TB HDD | 19'' Widescreen Samsung LCD Display
Mac OS X Snow Leopard 10.6.4 (Everything works except Safe Sleep) | Windows 7 Home Premium x64