Contemplate Affect RSS output

How can I add a node item to my rss output?

this is the normal item i get:

<item>
 <title>some kind of title</title>
 <link>www.somelink.com</link>
 <description>some description, etc etc</description>
</item>

but I want to add extra nodes inside the items:

<item>
 <title>some kind of title</title>
 <link>www.somelink.com</link>
 <description>some description, etc etc</description>
 
 <extranode1>extra data</extranode1>
 < extranode2>extra data</extranode1>
 etc etc

</item>

if I add stuff in the rss template it becomes available inside the ...
like <?php print $node->images[preview] ?> ...

any help ? :-)