Indeed it is possible, i own a MacBook Pro but did not want to pay silly money for a Mac Pro so i built an i7 biased PC and with the help of a certain website i managed to get Mac OSX to install. It is however not an easy process and could not get drivers for my sound card so i run the audio through the motherboard.
If you google for 'hackintosh' or 'OSx86' you will find tutorials, forums, custom installations and drivers.
As stevieblaze said, it's not easy and might take a lot of time and fiddling depending on your hardware, but in the end it is very possible (though I think this forum isn't really the place to discuss this as it has nothing to do with Max/MSP)
One simple way if you have quad core cpu, more of 4gb and fatser HD is with virtualbox, already exist images for virtual box, ready for download and install.
Anyway i suggest buy a mac, if no wnat spend money buy used mac mini.