In order to enable only week selection on clicking a date in RadCalendar you could use this
code library. The highlighting for a week is illustrated in a code library located here
I am attaching a sample project illustrating the functionality of the two libraries combined. I hope it would be helpful to you.
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 the blog feed