We've already "warned" you that we are going to do this. Here is the first demonstration of what you can do on PS3 with the use of game backups! Just grab Game Graphic Studio and play with your .img files and there it is!
PES 2010 will be fully editable, as much as Xbox version is, with the only difference being that (for now) you can't edit the Option File from your PC, but you may be able to extend the current file size (as opposed to X360 where it's not possible to do that). Just find a way to Jailbreak your PS3 and go have fun!