Adding a div to the right that makes the page scroll

Morning all,

I'm developing a site that detects the window size and calls the css accordingly.

The problem I have is that I've just been told (been working on the site for 4 months and it goes live today) that they want a banner to appear on the far right even if the screen isn't big enoguh to accomodate it (left/right scrolling). Despite my protests they want this done.

How can I set a div to be seperate from the main site and sit on the far right forcing the scrolling?

Thanks in advance.