if you have the supercard ... what you do is ...

download the HOMEBREW rom
apply a specific game patch for the specific HOMEBREW
(you need to do this because of the way the GBA or NDS rom save works)
after you're patched (use a .pff program) ... click and drag the patched HOMEBREW rom from your PC to your SD card. (you'll need a memory card reader)

remove the card from the reader and insert into the supercard.