Hi,
Using a bought copy of the upgrade disk I managed to use your tutorial to upgrade a working ideneb install to snow leopard! Thank you SO MUCH, you are the greatest!!

Some things:
1. adding EFI means adding a long list of digits to the com.apple.Boot.plist and it is based on your graphics card. I used "EFIStudio" , entered my EFI in the file (which you later copy from the USB to the HD in /Extra/com.apple.Boot.plist)
2. the UUID of my computer (you can find it in "apple->about this mac->more info->hardware under "hardware UUID") was already in the plist when I opened it, which brings us to:

3. I did not do exactly as written here. this tutorial is for a new install and I upgraded a current install, somehow it worked (maybe because I was based on ideneb to begin with?), after installing from USB I booted from the USB again but chose the HD I upgraded. the OS started ok (no video :-( ) but could not install chameleon for some reason. I didn't get it installing until now.. but I can boot from the HD now (after copying all of the Extra/ and boot files and changing as written in first post) and now the OS works.. so I don't know what was that chameleon failed to install all about.

Anyway, thank you so much for the howto, I really admire all you people taking the time to make this possible!!