I tried many ways to boot Ubuntu on my mac os. I do not have an internal cd drive but wen I tried to install it using the external cd drive(from apple), the drive does not work (Apple made it clear that u cant do this). I tried using many tools. I downloaded the amd64+mac edition and copid it to my usb using unetbootin.. it said that it would not boot of mac but the instructions on another blog was that it has no problems as the iso will take care. it also instructed to install refit and it worked for him but dosent boot for me. I even tried the terminal method of installing but didn't work... please help me out