Script to change mac address

I need a script to change ether1 interface mac address randomly or from a list that i have set before If ping to 8.8.8.8 fails .
Can anyone help please ?

Why do you need this?

Streetpassing for 3DS

MAC address to ping to 8.8.8.8 in relation to this? https://www.nintendo.co.uk/Hardware/Nintendo-3DS-Family/StreetPass/StreetPass-114943.html

http://forum.mikrotik.com/t/script-to-change-mac-address/82868/1