I'll certainly try to write up the steps required when I get chance (maybe tomorrow but if not at the weekend), missing out where I messed up due to my own stupidity though like thinking the eMMC wasn't flashing as it paused at 20%, and cancelling it - not a good idea, for anyone wanting to try it..

As for the image, I'd gladly post it but it is over 200Mb big, so it's probably easier just to show a screengrab of the bytes I changed (see attached). I can't take credit for this idea as it was DrWilken who came up with it - see this post. I just found that it's in fact possible to go over 9999 for the partition. Do please note that the filesize must remain unchanged, I simply shifted the 0D 0A bytes along, removing one 09 byte in the process, which is only a tab anyway and not needed.