Private Sub UserForm_Initialize()
    NonEmptyCellRef
End Sub

Private Sub NonEmptyCellRef()
Dim oTbl As Table
Dim i As Integer
    Set oTbl = ActiveDocument.Tables(1)
    With oTbl.Range
        For i = 1 To .Cells.Count
            If Len(.Cells(i).Range) > 2 Then
                ComboBox1.AddItem .Cells(i).RowIndex & ", " & .Cells(i).ColumnIndex & "^"
            End If
        Next i
    End With
End Sub