Bulk Update Attribute Prices

I have download products that are priced solely by attribute. Is it possible to change product-attribute prices by a percentage or fixed amount? It is possible to update 1 product's prices and then copy to the Category or to selected products but the latter is tricky because the interface relies on highlighting products in what could be a very long list...

Thanks,
Ric

As usual, the zenners get very quiet about things that are handled well in other carts and poorly in zen. The best way is to make sure each price attribute type is set with a unique price so that you can do a bulk update from phpmyadmin. If I know all my XXL sizes are set to +10, and that all other sizes and pockets etc have different prices, then all I need do is update the products_attributes table where options_values_price = 10.

UPDATE products_attributes SET options_values_price = '15.0'
WHERE options_values_price = '10.0' AND options_values_id = '5'

UPDATE products_attributes SET options_values_price = '15.0'
WHERE options_values_price = '10.0' AND options_values_id = '6'

I looked in the table products_options_values for the options_values_id (products_options_values_id) and the corresponding products_options_values_name