Mac Pro + ESXi 5.1: video card passthru problem

Hello,

I've installed VMware ESXi 5.1 on my Mac Pro (model 5,1). I've created a Windows Server 2008 R2 virtual machine, and configured ESXi so that the Mac Pro video card is attached to the VM via VMDirectPath I/O. The windows VM boots and makes use of the physical video card: its desktop is displayed on the Mac Pro's screen.

Doing the same thing with a Mac OS X 10.6 VM yields to a non-bootable state. The Mac OS X VM will boot only if I remove the PCI device from the VM configuration.

Is there any way to use the (Apple provided) ATI video card of my Mac Pro into a Mac OS X VM on top of ESXi?