The problem is that most distros mount the cdrom the wrong way (at least from what I can tell), causing the partial boot problem. The solution is to "burn" the iso to a usb drive using dd.
It's been a while since I've used OS X, but the commands should go something like:
diskutil list/code]
insert the usb drive to burn too and rerun
[code]diskutil list/code]
Figure out which drive number OS X assigned to the USB drive, this should be fairly obvious as it should be the only new entry in the command's output.
Now run
[code]sudo dd if=/path/to/BT.iso of=/dev/diskX bs=1m
Where X is the drive number that you determined earlier. If it throws an error about the 1m not being a real number use 1M instead. dd will not show any progress, but generally for me it takes around 10 minutes, but (obviously) that depends on the size of the iso. You can have it display how much of the iso is copied though by sending it the USR1 single. Something like
kill -USR1 <pid>
where the pid is the process id of dd, something that you can find through the top command, or ps -A.
Finally, boot the cd-rom, but have the newly burned usb drive inserted, now when it searches for the live filesystem it will find it residing on the usb, and will boot into the distro.