BCGSuite for MFC
BOOL CBCGPCalendar::SetSelectedRange ( const COleDateTime &  date1,
const COleDateTime &  date2,
BOOL  bNotify = TRUE,
BOOL  bRedraw = TRUE 

Selects dates range

Use this method to select dates range. If bNotify is TRUE, the calendar calls OnSelectionChanged() (which in turn sends out a notification message BCGM_CALENDAR_ON_SELCHANGED).

date1The first date in range.
date2The last date in range.
bNotifyIf TRUE, the calendar sends "selection changed" notification.
bRedrawIf TRUE, the calendar will be redrawn to reflect the new selection state.