If you can, I must say "thanks". XD
In fact, I think that no people have tried it , so I can't ensure that there's no bug in this hack.
If you or other people can try to do it yourself, I think I can move the thread to "tutoriales GBA". I think things called tutorials should be without bug haha... Other threads are not important, as this one is relatively a big project which made me spend a whole afternoon to do it