It's possible to achieve that, but it will not work right out of the box and you'll do some hard-coding.
Each button in that navigation has a unique ID of its own e.g. btnDay, btnMonth etc. You can use those to hook styles to offset the buttons. One possible way is to use negative left / right margins.
However, the styles might vary from skin to skin so a unified solution will be unlikely.
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed