[libvirt] Where to get precompiled qga-vss.dll from ?

Hi, I want to work with "guest-fsfreeze-*" commands in Windows 2008 guest VM. Host is CentOS 6.4. Windows 2008 is running QEMU VSS provider. When "guest-fsfreeze-*" commands are invoked from host, response received is "This is not supported". I am following http://lists.gnu.org/archive/html/qemu-devel/2013-02/msg01963.html. Regards, ~Puneet