After months searching for something similar i found this guide for trying to falsh an xg-flash 256M.
I have followed this guide using .gba files and -bin files created with pogoshell and whit 3 different nds cards.
Here an image of my cards
i had different errors. with m3 and dstwo:
and...
sorry, beein trying to find this file that's been right in front of me for a month now, only to find broken links, and google to prove that it's completely worthless.