You didn't had to delete the EFI partition. If you want a dual boot on mac you need to use this : rEFIt - An EFI Boot Menu and Toolkit
after instaling the refit boot loader for mac you need to go to : https://help.ubuntu.com/community/MacBook and chose your mac version. and folow the steps to installing even if it's for ubuntu (backtrack is a ubuntu based OS)
You'll need to make a new partition for backtrack and install grub on that partition. Refit will help you at startup to switch between the 2 OS. Don't forget that mac doesn't have a BIOS and that's why you need refit.
Hope this helps
To repair the problem at it is .. you'll need to install grub on the sda3 and after add to the grub the mac OS root partition so you'll be able to access both from the grub menu.