Step 0: Open your terminal window, Login as root and type the following commands ...
ifconfig | grep HWaddr /* This lists your mac addresses eth0 and wlan0 */
ifconfig wlan0 down /* Closes your current MAC adddress*/
ifconfig wlan0 hw ether [type preferred address e.g 00:A0:22:A1:12:DD]
ifconfig wlan0 up /* adds new mac address */
ifconfig wlan0 /* test setup, you should now see the new address you entered */