Thanks for the quick answer BlackRockS.
I did find something interesting in your exemple but actually I've noticed that I was incomplete in my post!
What I try to do by macro is to change the primary (or secondary) dimension label orientation like you can do in the property box, you know the "-", "/" or "|" modes!
Thanks again BlackRockS.
Just in case people have personal edition and can't open the file... this is the macro from the above attachment.
set chart = ActiveDocument.Sheets("Main").CreateBarChart
set p = chart.GetProperties
'p.ChartProperties.MajorDimensionTextMode = 0 'horizontal -
'p.ChartProperties.MajorDimensionTextMode = 1 'vertical |
p.ChartProperties.MajorDimensionTextMode = 2 'inclined /