Win32::AdminMisc Works great for this too. And it is very easy to do:

#!/usr/bin/perl -w
use strict ;
use Win32;
use Win32::AdminMisc;

Win32::AdminMisc::SetEnvVar( "UUID", "TEST-TEST", ENV_SYSTEM ) ;
Win32::AdminMisc::SetEnvVar( "UUID", "TEST-TEST", ENV_USER ) ;
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"Nothing is sure but death and taxes" I say combine the two and its death to all taxes!