This is the link,
http://www.malwareremoval.com/donations.php
He also informed me that you do not need a paypal account, you can use a credit card to donate. There is also no need to worry about identity theft, etc because your computer is clean and paypal is probably the most trusted internet pay method.
I hope even though there is no way to mail it, you will still donate. These donations really help to keep our volunteer site going.
Thank you,
Mike