[Help needed] Boot ROM from SDcard

My eMMC is probably dead, but I can still access CWM recovery, so there must be a way to tell the bootloader to fetch boot files on the external SDcard, right?
I found this http://forum.xda-developers.com/show....php?t=1572924 and it is exactly what I want, can anyone help me modify the zip file in a way to make it work on e970?