Generate password hash
No - a simple sha512 wouldn't be the same because its lacking the "salt" added by Drupal that prevents the "ability to use pre-hashed lists of candidate passwords" against your database (among other things). Its a security improvement over D5/D6 where a simple md5 update query could reset a user's password. 

You might get more mileage out of connecting to the password-hash.sh script (in the scripts folder of your Drupal installation) in your VB script using whatever the equivalent to PHP exec() is in VB..