I am not a Mac person (I have seen one once), I can say that others have been able to get them to pxe (netboot) boot.
There are some additional steps required to netboot these boxes. Understand this isn’t a fog problem, but rather a Mac problem with pxe booting.
Additional discussion on netbooting.
I also suggest that you read these threads because there are other useful tips.
And finally one of the devs has first hand experience with this things called Mac, that may have some insight to netbooting these things. @Sebastian-Roth