Using Kakewalk 3.1 (USB stick) as per instructions, I successfully installed 10.6.5 (Snow Leopard), on my GA EX58-UD3R. Unfortunately, audio isn't working. Although, in System Preferences/Sound it shows "Internal Speakers" & TWO "Line Out". The EX58-UD3R lists a ALC888 codec. What kexts do I need in /System/Library/Extensions or /Extra/Extensions?
Use Multibeast to install the right kexts, it's pretty self explanatory when you use it. Install the rollback plus the ALC888 kext and system utilities.