How about
Code:
Sub NumberTable()
Dim oRow As Row
Dim oRng As Range
Dim lCount As Long
Dim wCount As Long
Dim i As Long
lCount = 1
wCount = 1
With ActiveDocument.Range.Tables(1)
For i = 1 To .Rows.Count
Set oRow = .Rows(i)
If i Mod 2 = 0 Then
Set oRng = oRow.Cells(1).Range
oRng.End = oRng.End - 1
oRng.Text = "L" & Format(lCount, "000")
lCount = lCount + 1
Else
Set oRng = oRow.Cells(1).Range
oRng.End = oRng.End - 1
oRng.Text = "W" & Format(lCount, "000")
wCount = wCount + 1
End If
Next i
End With
lbl_Exit:
Set oRow = Nothing
Set oRng = Nothing
Exit Sub
End Sub