First you need to find the template that is in charge for the latest news.
In this case it is: design/standard/templates/toolbar/full/node_list.tpl
Then you create an override template for it. There are a few different methods to do this. In this example I just saved the template to design/plain/override/templates/toolbar/full/ as plain is my sitedesign.
In this template you have to look for "fetch( content, tree,..."
