How do you code a featured image into an XML as a jpg link, instead of using a data-id number?

All I want to do is get WordPress’s featured image XML code to use a jpeg link as the meta_value, instead of the image gallery data-id number.

Basically change this code:

<wp:postmeta> 
        <wp:meta_key><![CDATA[_thumbnail_id]]></wp:meta_key>
        <wp:meta_value><![CDATA[202466]]></wp:meta_value>
</wp:postmeta>

To something reading like this:

<wp:postmeta> 
        <wp:meta_key><![CDATA[_thumbnail_id]]></wp:meta_key>
        <wp:meta_value><![CDATA[http://xxxx.com/wp-content/uploads/xxxx.jpg]]></wp:meta_value>
</wp:postmeta>

I appreciate the help, hopefully its something simple enough.