This might work:

If $winver=2
$TempString = READVALUE("HKEY_LOCAL_MACHINE\Enum\Network\MSTCP\0000", "Driver")
$Mask = READVALUE("HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Class\$TempString", "IPMask")
Else
$TempNumber = READVALUE("HKEY_LOCAL_MACHINE\SYSTEM\Select", "Current")
$TempString = "ControlSet00"+$TempNumber
$NetCard = ENUMKEY("HKEY_LOCAL_MACHINE\SYSTEM\$TempString\Services\NetBT\Adapters",0)
$Mask = READVALUE("HKEY_LOCAL_MACHINE\SYSTEM\$TempString\Services\$NetCard\Parameters\Tcpip", "SubnetMask")
$Dhcp = READVALUE("HKEY_LOCAL_MACHINE\SYSTEM\$TempString\Services\$NetCard\Parameters\Tcpip", "EnableDHCP")
Endif