MAC address spoofing issues on my mac

[Joe 90]

Its a huge pain in the backside but on my connection I'm only allowed 3 devices authenticated by their MAC.

I've got 5 devices though! So I have to do a little bit of MAC spoofing.

On my xbox that works fine. However on my mac it seems to return to default after a reboot.
I don't know a whole lot about the terminal yet but i'm getting used to a few commands;
sudo ifconfig en0 ether 'mac address'

should that do what I want or is it that command that results in the reset when the machine reboots??