Modify the macro that Doug posted, like this:
Sub x()
Dim source As Document, target As Document
Dim i As Long
Set source = ActiveDocument
Set target = Documents.Add
With source
For i = 1 To .Comments.Count
target.Range.InsertAfter _
"[" & .Comments(i).Scope.Text & "] [" & _
.Comments(i).Initial & "][" & _
.Comments(i).Range.Text & "]" & vbCr
Next i
End With
End Sub