If you find SC 2012 EndPoint Protection fail to install on Windows 8, it may be because of a registry key missing. Troubleshooting a Windows 8 Client I read trough C:\windows\ccm\logs\EndpointProtectionAgent.log I found this error
“Failed to get EP event message under registry key SOFTWARE\Microsoft\CCM\EPAgent”
As a temporary solution I created an empty package with a program running command line: reg add “HKLM\SOFTWARE\Microsoft\Microsoft Security Client” and deployed this program to my Windows 8 Clients.