OKay, yet, haven't found much help so i'll just write down EVERYTHING i've done so far. Maybe someone will know what i've done wrong...
Installed from scratch, I have a partition on my HDD with the installer files for Lion X.7.2
I have to use GraphicsEnabler=no everytime I boot with rBoot...
now, the multibeast part :
I have my mobo's DSDT.aml on the desktop, it is the Z68XP-UD4 F4
64bit GraphicsEnabler=no
AppleHDA Rollback
I also manually installed chimera 1.8 'cause it's supposed to support the AMD Sapphire HD6670
Then rebooted... still stuck on the bootscreen with a wheel that's spinning forever.
rBoot + GraphicsEnabler=no still works so I kept on working this way.
I had some kernel panicks when plugging USB devices so I went to Miscellaneous and checked FAKESMC Plugins > Motherboard Plugins + AMD RADEON Plugins (thinking it could help my situation) + The IOUSBFamily Rollback
At least the USB is not freezing now... And i'm still able to boot using rBoot + GraphicsEnabler=no ... But I am Unable to boot without it...
And it's confirmed that using the latest Chimera, My graphics are set with kBulrushes which should be fine...