How to bless a partition using a custom EFI-boot file with non-conforming directory structures and/or file names?

Is there a guide on how to bless a partition for booting, one that doesn't have the default /System/Library/CoreServices/boot.efi structure? For example, I installed GRUB on the default EFI System Partition (/dev/disk0s1in OS X, /dev/sda1 in Linux) and I have the file /EFI/arch_grub/grubx64.efi that I want to use instead of /System/Library/CoreServices/boot.efi. Normally, following the standard structure, I would copy grubx64.efi to /System/Library/CoreServices/boot.efi and also touch /mach_kernel in the partition I want to make bootable, then I'd run the following to bless the partition: # bless --folder= --file=/System/Library/CoreServices/boot.efi --setBoot # bless --mount= --file=/System/Library/CoreServices/boot.efi --setBoot To install GRUB, I followed the instructions in the Arch Linux Beginners' guide, which leaves me with (something like) /EFI/arch_grub/grubx64.efi file, where word arch_grub is arbitrarily chosen. Then running the following commands succeeds with no errors: # bless --folder= --file=/EFI/arch_grub/grubx64.efi --setBoot # bless --mount= --file=/EFI/arch_grub/grubx64.efi --setBoot But the partition doesn't show up in the Apple boot menu, and sudo bless --verbose --info shows: ┌─[02:31:54/trusktrs-MacBook-Pro/trusktr//tmp] └─╼ sudo bless --verbose --info /tmp/boot/ Mount point for /tmp/boot/ is /private/tmp/boot GPT detected Booter partition required at index 2 System partition found Preferred system partition found: disk0s1 Returning booter information dictionary: {type = mutable dict, count = 3, entries => 0 : {contents = "System Partitions"} = ( disk0s1 ) 1 : {contents = "Data Partitions"} = ( disk0s1 ) 2 : {contents = "Auxiliary Partitions"} = ( ) } I made sure to touch /mach_kernel then unblessed and re-blessed the partition using the same commands but no luck. I bet I'm missing something(s) simple and that it's not difficult to do what I want, but I'm not exactly sure what I need to do. Any tips/ideas/suggestions?