The Code

Here is the quick and dirty VBScript that solves the problem:

set net = CreateObject("WScript.Network")
workstation=net.computername
location=left(workstation,2)
printername=""
select case location
  case "L1"  printername="L1 LaserJet"
  case "L2"  printername="L2 LaserJet"
  case "L3"  printername="L3 LaserJet"
End Select
if printername<>"" then net.SetDefaultPrinter(printername)
set net = Nothing