• Cygwin SSHD installed and setup
• backuppc local/domain account with admin privileges (for taking VSC)

Specifically you do have to use a password, once. Create a Scheduled task logged in on the Windows server as the backuppc user (the user that you'll be logging into the sshd with) - should probably be a service account. Scheduled task will c:\cygwin64\bin\bash.exe the bash script that does the stuff, including the VBS that creates the VSC

It will work without a password!