Your best bet is to get Parallels 7
Originally Posted by WPGH
(7 not 10, there is an exploit with 7 that allows you to use the 2 week trial forever
) and download Steam, Cod4, Extreme injector, and the hack itself. If you are using a mac that has some power (Hopefully you have an iMac 27' Mid 2011 or newer) it should run relatively good. Around 50-60 Frames.
Hopefully I helped you out, and not to be rude, but you should invest in a Windows based PC.
...If you can afford a Mac, you can get a decent PC...