public Color Stroke { get; set; }

Public Property Stroke As Color

private void mapControl1_DrawMapItem(object sender, DrawMapItemEventArgs e) {  
  if(e.Item is MapPie) {  
    DrawMapSegmentableItemEventArgs args = (DrawMapSegmentableItemEventArgs)e;  
    for(int i = 1; i < args.Segments.Length; i += 2){  
       args.Segments[i].StrokeWidth = 2;
       args.Segments[i].Stroke = Color.Red;  
    }
  }  
}

Private Sub mapControl1_DrawMapItem(ByVal sender As Object, ByVal e As DrawMapItemEventArgs)
    If TypeOf e.Item Is MapPie Then
        Dim args As DrawMapSegmentableItemEventArgs = CType(e, DrawMapSegmentableItemEventArgs)
        For i As Integer = 1 To args.Segments.Length - 1
            args.Segments[i].StrokeWidth = 2
            args.Segments(i).Stroke = Color.Red
        Next
    End If
End Sub