Ok, so far I have been able to Install Mountain Lion successfully. I also installed MultiBeast.
My initial problem remains, though. When I reboot without any flags, all I get is the Apple logo for 10 seconds and then the screen goes blank. When I insert "GraphicsEnabler=No PCIRootUID=0 npci=0x3000 cpus=1" together with my SSD boot disk, it boots up normally.
I have set "GraphicsEnabler=No" in "org.chameleon.Boot.plist" and saved, and I also downloaded KextBeast and VoodooTSCSync.kext and placed both on my Desktop, ran KextBeast and it said the installation was successful. When I look into Library/Extensions/, I can't see it anywhere, though.
Also, I have tried yo_mang's way, editing the two files "org.chameleon.Boot.plist" and "smbios.plist", but to no avail.
I will call it a day now, as it is 3 in the morning here in Germany. I'd be glad and thankful for any suggestions, as to how I can fix this issue...
See you tomorrow,
jageffen