I am having a very hard time tracking down the modified copy of this image (series2 649). I was able to remove my prom and even read it (surprising, considering the removal was a bit dicey). However, the mod instructions I found talk about taking part of the image and decompressing it, editing it, and pasting it back in over the top of part of the original image. This is a little out of my depth without more specific "how to" info on the decrypt, etc. So I'm searching for the modified copy of the image. Please PM me if you have it.
With all due respect, if you can't get as far as modifying the binary PROM image, you're going to have some serious issues getting the rest of the hacks in place. The PROM code modification a very basic and simple step.
Although the specific thread titles left my mind long ago, there are several topics that cover exactly how to perform this operation. Some digging will likely be required to find them.