Latest Posts I believe is using the JS option for Content Islands. News you'd have to have a JS output or your server needs to have the ability for includes. If you're using the PHP Accellerator you can use a simple PHP include (which I enjoy)...
[code][/code]Mainly do it with a blank page (output as plain text) in the design that you'd like it to be seen.
Its not too difficult if I recall, but if you've seen my sites you'll notice that I don't use the sidebar so I'm not 100% sure.