In order to edit this you need to change the template of the ScheduleView. You could generate the whole style of the control very easy with Expression Blend. Just drop a ScheduleView control on the design surface, right-click it and choose from the menu Edit Template->Edit a Copy
Then search within the template for a RadButton with set command: RadScheduleViewCommands.SetDayViewMode. This is the header you are refering to - you could change everything you need. The VisibleRangeChanged
event is fired, because the view is changed.
Hope this information helps.
All the best,
the Telerik team