This is a useful blog on how to set it up, as mentioned, some shopping carts already have the VAU and Mastercard Auto Updater built in, is this possible with 1ShoppingCart too? http://blog.unibulmerchantservices.com/how-visa-account-updater-works-and-how-much-it-should-cost-you/
Here is a the Visa Account Updater from Visa: http://usa.visa.com/merchants/grow-your-business/processing-solutions/account-updater.jsp
It is ideal for recurring billing as it means we won't lose our customers when their cards expire or they are issued a new one because it was lost/stolen. This is really big.
We are having the same issue too. For example:
Digital books - VAT applied for all countries
Paperback books - VAT applied for only a few countries such as Spain
As this is required by law, I really think 1ShoppingCart should implement this functionality asap.