in a vbs file, put:
Set WshNetwork = WScript.CreateObject("WScript.Network")
Set Printers = WshNetwork.EnumPrinterConnections
For i = 0 to Printers.Count - 1 Step 2
WScript.Echo i,i+1,"",Printers.Item(i),Printers.Item(i+1)
Next
WshNetwork.SetDefaultPrinter Printers.Item(0)
Or...