HTMLmail : how to make a node.tpl for newsletter via simplenews

Hi

I'm using simplenews to create newsletters and i need to make a tpl to theme it.
So as usual for theming nodes, i would to make a htmlmail-simplenews-node.tpl.php containing elements from my newslsetter content type like image, viewreference and body...

what's the way to do that ?
does exist example template or tuto ?

thanks