Are you wanting to dual-boot, or run Kali as your only OS?
To create the install USB, I just used the DD method.
Code:
sudo diskutil unmountdisk /dev/diskX
sudo dd if=kali_iso_filename_here of=/dev/diskX bs=1m
Replace X with the correct disk number for your USB stick.
After that, reboot holding down the option/alt key, and select the yellow/orange EFI icon.
Buuuuut, that's just me. I got that to work with MacBook Pros from 2007, 2012, and 2015.
Anywho, I hope that helps.
Also, if it makes any difference, I am still trying to troubleshoot getting the Graphical desktop to come up on my 2007, so perhaps this is the trouble you're having? I can get it up and working in Text/command line mode.