To disable guest time sync on virtualbox 4.3 type:
vboxmanage setextradata MyVM VBoxInternal/Devices/VMMDev/0/Config/GetHostTimeDisabled 1
To disable guest time sync on virtualbox 4.3 type:
vboxmanage setextradata MyVM VBoxInternal/Devices/VMMDev/0/Config/GetHostTimeDisabled 1