PayPal Multiple Emails by Category

Please extend this Plugin to allow a different PayPal email for each category. Currently it only allows one category to specify a PayPal email. We need each product category to have the ability to go to different PayPal accounts. Or please advise how we can modify it ourselves. It already has to save a category and PayPal email values, so seems it would be fairly easy to have it save multiple category/PayPal email pairs. Please advise. Thanks. Rose