http://www.windows-noob.com/forums/index.php?/topic/1942-activate-win7-mak-in-ts/

To enable standard user activation on a KMS client, add a new DWORD registry value named UserOperations and set its value to 1. Create this value in the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SoftwareProtectionPlatform registry subkey.

When complete, administrative rights are no longer required for some operations, such as installing a product key (slmgr.vbs /ipk), installing a license (slmgr.vbs /ilc), or rearming (slmgr.vbs /rearm). This means that a standard user can switch a KMS client to MAK activation, manually activate a computer, and—if necessary—replace an existing MAK with a new MAK. Doing so is not recommended, however, because it lowers security on the computer.