Thanks to user for the short tutorial on how to change your MAC address. He also listed methods on how to do that under several Linux distros, including with a program called MACChanger.

It’s a little different in FreeBSD and you cannot issue the full command without and error. You can create a file named /etc/start_if.em0 with the following content:
lladdr be:ef:be:ef:be:ef
You can also insert:
ifconfig_em0=”inet netmask″
ifconfig_em0_alias0=”link 2b:3b:4b:5b:6b:7b”
into a login script (/etc/rc.conf)