FarPoint.Win.Spread.CellType.DateTimeCellType dt = new FarPoint.Win.Spread.CellType.DateTimeCellType();
string[] dNames = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
string[] mNames = {"Jan", "Feb", "Mar", "Apr", "May", "June", "July", "Aug", "Sep", "Oct", "Nov", "Dec",""};
string[] sdNames = {"SU", "M", "T", "W", "TH", "F", "S"};
string[] smNames = {"J", "F", "M", "A", "MY", "J", "JY", "AG", "S", "O", "N", "D",""};
string okbutn = "Accept";
string canbutn = "Decline";
dt.DateTimeFormat = FarPoint.Win.Spread.CellType.DateTimeFormat.UserDefined;
dt.UserDefinedFormat = "dddd MMMM d, yyyy";
dt.DayNames = dNames;
dt.MonthNames = mNames;
dt.ShortDayNames = sdNames;
dt.ShortMonthNames = smNames;
dt.SetCalendarText(okbutn, canbutn);
fpSpread1.ActiveSheet.Cells[0, 0].CellType = dt;
fpSpread1.ActiveSheet.Cells[0, 0].Value = System.DateTime.Now;
fpSpread1.ActiveSheet.Columns[0].Width = 130;