The big difference between Macs and PCs is that all Macs are the same, while all PCs are different, from their hardware. So, a solution for booting XP that works on my Mac will work on your Mac, because we use the same drivers for our Macs.
But for booting OSX on PCs, each PC really is a different case, because you need drivers that are suported by OS X. That is why the author of this article had to build his own PC which he knew would have most chances to run OS X. OS X was not meant to use third party drivers like XP does. In other words, for XP, a Mac is just another PC, while for OS X, a PC is a total stranger, and you have to fool him he is on a Mac to boot!
Aurel