On your domain connected Windows 8 workstation open an elevated Command Prompt (Command Prompt (Admin)) and run the following commands:
cd /d %windir%\winsxs
dir *.admx /s /b > %USERPROFILE%\Desktop\admx.txt
dir *.adml /s /b | find /i "en-us" > %USERPROFILE%\Desktop\adml_en-us.txt
mkdir %USERPROFILE%\Desktop\PolicyDefinitions
mkdir %USERPROFILE%\Desktop\PolicyDefinitions\en-US
FOR /F %i IN (%USERPROFILE%\Desktop\admx.txt) DO copy %i %USERPROFILE%\Desktop\PolicyDefinitions\
FOR /F %i IN (%USERPROFILE%\Desktop\adml_en-us.txt) DO copy %i %USERPROFILE%\Desktop\PolicyDefinitions\en-US\
This will copy all of the new templates from your Windows 8 machine to the GPO location.
Logon to your Domain Controller and browse to c:\Windows\ and rename PolicyDefinitions to PolicyDefinition.pre-8 then copy the PolicyDefinitions folder you just created on your desktop to your domain controller in c:\windows\. Finally open the group Policy Editor to access the new, upgraded templates.
Note: This process can also be used to import Windows Server 2012 templates into a Windows Server 2008 R2 based domain.