I meant to investigate this first more, but before I totally forget it (I still have some other projects going), I better document it here, at least:
It sometimes happens that someone accidentally installs Chameleon on his Mac, making it not boot any more.
I am not sure why this happens yet, but one suspicion I have is that Chameleon overwrites the EFI Partition's first sectors, which are unused when booting OS X on a PC, but necessary for booting on a real Mac.
Thus, I propose that the Installer tries to detect this. E.g, if it's really as I think, then the check would be to see if the first two sectors where boot1h gets written contain "EFI PART" in the first 8 bytes.
But maybe this is not the right solution. In any case, please add something to avoid this accident from happening, if possible.