I've got a Macbook Pro that I'm trying to outfit with Kali, as well as leaving the OS X and Win 7 installations alone. I've formatted a 50GB partition out (free space) on my main drive where I'd like to put this thing, but I'm just having some trouble getting to the point of install. Here are the steps that I've taken thus far:
I DL'd and installed the rEFInd bootloader, installed just fine (verified that it works too).
I formatted out my 4GB thumb drive (FAT32 as recommended from some other posts).
I DL'd the kali iso file and put it onto the thumb drive, renaming the file to boot.iso.
So my file structure has these two files in it so far:
efi/boot/boot.iso
efi/boot/bootX64.efi
After restarting I select my thumb drive and it takes me into a black screen that appears as so:

GNU GRUB version 1.99~rc1

Minimal BASH-like line editing is supported. For the first word, TAB
lists possible command completions. Anywhere else TAB lists possible
device or file completions.

grub>_

I don't really know a thing about grub, but from what I've read I'm on the right track. However I have no idea how to continue with the installation from here. Would anyone be willing to help me along with this? Much appreciated, thanks.

Best Regards.