Follow @astrofloyd's instructions, including:
- Obtain a copy of ISO 2 USB EFI Booter for Mac
diskutil listto find the node name of your USB drive- Format the USB drive with a single FAT32 partition (use
diskutil eraseDisk fat32 UNTITLED /dev/diskX) cdinto the drive andmkdir -p efi/boot(from the computer's root drive the path should look something like/dev/diskX/efi/boot)- Copy
bootIA32.efionto the USB drive and rename it:cp /location/of/bootIA32.efi ./boot.efi - Copy the Linux distribution
.isofile and rename it toboot.efi