Dim rng As Range
Set rng = Range("a2")
Worksheets(1).Shapes.AddTextbox(msoTextOrientationHorizontal, rng.Left, rng.Top, rng.Width, rng.Height).Select
    With .Selection
        'и т.д.

Private Sub Worksheet_BeforeRightClick(ByVal Target As Range, Cancel As Boolean)
Dim i As Integer
    With Worksheets(1).Shapes.AddTextbox(msoTextOrientationHorizontal, _
    Target.Left, Target.Top, Target.Width, Target.Height).TextFrame
        .Characters.Text = Target.Text
        .MarginLeft = 0
        .MarginRight = 0
        .MarginTop = 0
        .MarginBottom = 0
        .HorizontalAlignment = xlRight
            For i = 1 To Len(Target.Text)
                '.Characters(Start:=i, Length:=1).Font.Size = 5 + i
                .Characters(Start:=i, Length:=1).Font.Color = 256 + i * 100
            Next i
    End With
End Sub

Dim i As Long