In eBay seller services, there is a link for Mission Fish. Follow the links and register as a seller (CARES is already registered as a certified charity).
The only drawback is that you have to have a creditcard on file with mission fish from which they take your donation. We are waiting on our PayPal card so that we can just use the same account that the buyer pays into.
The auction can be started from a couple of different areas but the easiest is through the mission fish prompts. The persentage of the final sale price that is donated can be varied upto 100%. A donation over 90% qualifies for a reduced or free listing and final value fee.
I hope this is helpful for anyone interested.