Sometimes, the solution is so simple! Here is the solution that I found, based on your help:
xlsSheet.Range(xlsSheet.Cells(1, 1), xlsSheet.Cells(1, 1)).AddComment.Text strTMP
xlsSheet.Range(xlsSheet.Cells(1, 1), xlsSheet.Cells(1, 1)).Comment.Shape.ScaleWidth 1.75, False
This code enlarge the...