Aparentemente você está sem sorte. De acordo com Wikipedia :
Although Shadow Copy service will remain intact, the ability to create persistent shadow copies will be removed from the future versions of Windows, codenamed Windows 8 and Windows Server 8. Consequently, the Previous Versions feature which exposed this functionality will also be removed. Shadow Copy service will only be able to create volatile shadow copies for backup purposes. Microsoft says negative impact on performance and low usage is the reasons behind the removal of this feature. As for accessing older versions of the user file however, Microsoft will add a new component called File History to the aforementioned versions of Windows. This component will replace Backup and Restore.
No entanto, eu veria se há uma maneira de jogar com as opções de linha de comando Volume Shadow Copy (VSSAdmin). Eu não tenho o Windows 8 na mão, mas vale a pena dar uma olhada.
Por TechNet :
VssAdmin is used to create, delete, and list information about shadow copies. It can also be used to resize the shadow copy storage area ("diff area").
VssAdmin includes commands such as the following:
create shadow: Creates a new shadow copy
delete shadows: Deletes shadow copies
list providers: Lists all registered VSS providers
list writers: Lists all subscribed VSS writers
resize shadowstorage: Changes the maximum size of the shadow copy storage area
VssAdmin can only be used to administer shadow copies that are created by the system software provider.
VssAdmin is available on Windows client and Windows Server operating system versions.