I emailed Google about adding an eBay store - and they told me what to do - set some options in eBay to create an XML file/URL address and email the URL in a reply to the email - but two weeks later and it has not show up.
I'll have to search a little, I got involved in too many other things, and have done nothing with my eBay store for months. Send me a PM to remind me if I don't post a reply within a week. I doubt I deleted the message - it's buried in a pile of tens of thousands of email messages.
Here's instructions on how to download items from your eBay store. You can then reformat and upload to Froogle: pages.ebay.com/help/stores/contextual/export-listings.html