Well John...it is a bit beyond me but I would imagine if the program was written to operate with a bootloader and you tried to load the file it would come up with errors initially. But then , as the exert goes on to say , perhaps they use some sort of interpreter to access data.
But yes, the source code would be a big help.

If you run a disassembler on the hex files, will that give your programmer mate enough to go on...???

I have just downloaded a rather large tutorial on programming but it could take me quite a while to get through. Hope is to be able to do it one day.