A Live Boot Image for the Mac that Talks

[Linux for blind general discussion]

I don't have any experience with Macs or writing bootable images to
USB sticks(I just burn isos to DVD using wodim when I need to make a
new Linux disc), but my first two thoughts are:

1. Perhaps the Mac's bios isn't configured to allow booting from USB
media. I know I've had to get sighted assistance to fix the bios boot
order on every laptop and desktop I've acquired since going blind
before I could boot installation media to install Linux... I even had
to do it for a netbook that came pre-loaded with Ubuntu if memory
serves.

2. I could be wrong, but I believe the files needed for making a
CD/DVD bootable and making a USB stick bootable are different. If so,
even a properly written iso might not result in a bootable USB stick
if the iso only includes the files needed for booting from CD/DVD.
Again, no experience with making bootable USB sticks, so I might be
horribly mistaken.