Sub Test()
Dim NbPts, i
' Compte le nombre de points sur la courbe
NbPts = Worksheets(1).ChartObjects(1).Chart.SeriesCollection(1).Points.Count
ActiveSheet.ChartObjects(1).Activate
For i = 1 To NbPts
If i And 0 = 0 Then
' Si point pair
ActiveChart.FullSeriesCollection(1).Points(i).DataLabel.Select
Selection.Position = xlLabelPositionBelow
Else
' Si point impair
ActiveChart.FullSeriesCollection(1).Points(i).DataLabel.Select
Selection.Position = xlLabelPositionAbove
End If
End Sub