I found the information below in a response to a Vista UAC question. Will this work for Server 2008 x64 Enterprise? I would test but Lab is offline for power upgrade and I do not want to test in a production environment.
You have to execute this command remotely: reg.exe ADD HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System /v EnableLUA /t REG_DWORD /d 0 /f
and reboot the remote system afterwards (which can be achieved using shutdown.exe). To work with your file, you could use psexec.exe, it can work against a list of names. psexec is part of the pstools from Microsoft.