Thanks, Earthshine. Having the script functional only after login implies that I manually press the scroll lock key to turn on the keyboard, in order to insert the password: of course this is definitely not an issue, but if there is a way to make the process completely automatic I'd be really glad to follow it.
I've already tried to edit the registry, as argumentum also suggested above, but unfortunately the procedure doesn't work for me.
May I ask you what you exactly intend by running the .EXE as service? Is it something I can do recurring to Autoit and/or internal Windows features? Or do I need specific softwares instead?