The following example sets the pen attributes for a two-dimensional xy chart series. The GuideLinePen property returns a reference to a Pen object.
Private Sub Command1_Click()
' Set Guide Lines for 2D XY chart Series 1.
MSChart1.ChartType = VtChChartType2dXY
MSChart1.Plot.SeriesCollection.Item(1) _
.ShowGuideLine(VtChAxisIdX) = True
With _
MSChart1.Plot.SeriesCollection.Item(1).GuideLinePen
' Set Pen attributes.
.VtColor.Set 255, 255, 0
.Width = 10
.Style = VtPenStyleDashDot
.Join = VtPenJoinRound
.Cap = VtPenCapRound
End With
End Sub