Here is a nice tutorial that allow you to change ur MAC Address(Hardware Address OFf A specific Computer).
Tutorial to change MAC Address In Backtrack1] Open the terminal type ifconfig.(check your MAC Address)
2] In terminal, type ifconfig eth0 down this command is used for disabling the eth0 interface.
3] Now change the MAC address by using a simple command in backtrack macchanger –r eth0
4] Now type ifconfig eth0 up this command is used for enabling the eth0 interface
5] Again check your fake MAC Address By typing ifconfig.
To Know More details See the screen shots it will make you clear idea.
Thanks for reading if you want to learn more on backtrack keep in touch with darksite