I'll give that a try, once I get it booting again (stopped booting today, but I think it's because my bios got reset to factory default). Regarding the drivers, GraphicsEnabler is set to true in org.chameleon.boot.plist, and I used the scripts from the linked guide to install ML. I didn't install drivers for nvidia after that, since I couldn't find any for ML.
So I have Mountain Lion running smoooooth, but one thing that annoys me is that I only get output on the VGA port of my NVidia GTS 250. The DVI and HDMI ports don't even show up in System Information. I've attached some screenshots, hopefully it will be useful to determine the problem. How can I enable the other two? I followed this guide: [GUIDE] A fast and easy way to install Mountain Lion