SpoofMAC

#!/bin/sh
. /etc/rc.common

StartService ()
{
    ConsoleMessage "Running SpoofMAC script."
    /usr/sbin/networksetup -setairportpower en0 on
    /System/Library/PrivateFrameworks/Apple80211.framework/Resources/airport -z
    /sbin/ifconfig en0 ether `python -c 'import random;print ":".join("%02x" % octet for octet in [random.randint(0,64) << 2] + [random.randint(0,127) for _ in range(5)])'`
    /usr/sbin/networksetup -detectnewhardware
}

StopService ()
{
    return 0
}

RestartService ()
{
    return 0
}

RunService "$1"

StartupParameters.plist

{
    Description      = "SpoofMAC";
    Provides         = ("SpoofMAC");
    Requires         = ("Network", "Disks");
    OrderPreference  = "None";
}