Parece que es un paquete a instalar... virtualbox.org/manual/ch04.html
Invitado = Windows, anfitrión = MacOsX.
For the basic Direct3D acceleration to work in a Windows Guest, you have to install the Guest Additions in "Safe Mode".
f you prefer to mount the additions manually, you can perform the following steps:
Start the virtual machine in which you have installed Windows.
Select "Mount CD/DVD-ROM" from the "Devices" menu in the virtual machine's menu bar and then "CD/DVD-ROM image".
In the Virtual Media Manager, press the "Add" button and browse your host file system for the VBoxGuestAdditions.iso file:
Back in the Virtual Media Manager, select that ISO file and press the "Select" button. This will mount the ISO file and present it to your Windows guest as a CD-ROM.
Unless you have the Autostart feature disabled in your Windows guest, Windows will now autostart the VirtualBox Guest Additions installation program from the Additions ISO.
If the Autostart feature has been turned off, chooseVBoxWindowsAdditions.exe from the CD/DVD drive inside the guest to start the installer.
The installer will add several device drivers to the Windows driver database and then invoke the hardware detection wizard.
Depending on your configuration, it might display warnings that the drivers are not digitally signed. You must confirm these in order to continue the installation and properly install the Additions.
After installation, reboot your guest operating system to activate the Additions.