You need proper access to the remote registry to be able to connect to Windows 7 (&8) systems in this manner.
There is a guide here on how to successfully connect to the remote registry. It gathers all the disparate information needed - enabling file and printer sharing, enabling the remote registry service and adding the specific user that is connecting to the remote registry into the HKLM\SYSTEM\CurrentControlSet\Control\SecurePipeServers\winreg
.
Once all these tasks have been performed on the remote system, you should be able to connect remotely to it using WinRT://remoteHost
. I tested it on some systems I had and it works.
This is would probably all work automatically if the system was a domain bound system and the account being used to connect was a domain adminstrator account.