http://get-powershell.com/post/2008/08/13/PowerShell-Function-Set-IPAddress.aspx
1: function Set-IPAddress {   2:         param(  [string]$networkinterface,
   3:                 [string]$ip,
   4:                 [string]$mask,
   5:                 [string]$gateway,
   6:                 [string]$dns1,
   7:                 [string]$dns2,
   8:                 [string]$registerDns = "TRUE"
   9:          )
  10:         
  11:                 
  12:         #Start writing code here
  13:         $dns = $dns1
  14:         if($dns2){$dns ="$dns1,$dns2"}  15:         $index = (gwmi Win32_NetworkAdapter | where {$_.netconnectionid -eq $networkinterface}).InterfaceIndex  16:         $NetInterface = Get-WmiObject Win32_NetworkAdapterConfiguration | where {$_.InterfaceIndex -eq $index}  17:         $NetInterface.EnableStatic($ip, $mask)
  18:         $NetInterface.SetGateways($gateway)
  19:         $NetInterface.SetDNSServerSearchOrder($dns)
  20:         $NetInterface.SetDynamicDNSRegistration($registerDns)
  21:         
  22: }