Mercyful, you're a genius!!!
With your "DUMPS_FIX_PACK_8_iNTERNAL_PSP-PLAYASiA" package (that I didn't know it existed!) and this command:
xdelta patch ULES-00979.xdt 2ch-lseg.iso "Simpsons, Los - El Videojuego (Spain).iso"
you have made my day!!
Thank you very much, Mercyful!
Regards from Buenos Aires, Argentina...
GABRIEL