The Supercard DSONEi / Mini have received an update to their firmware/bootloader, making them compatible with the 3DS (in DS mode). A plus about this update is that it is in the .NDS form, meaning it's a program you can run on the flash cart itself (no need for the firmware writer device).
QUOTE(Instructions)
Usage:
Unzip the grade file to the TF card.
Find a DS console which support DSONEi/mini to run the upgrade file from EOS menu. (find the file, press A)
Follow the instruction, press B, DSONEi / Mini is upgrading.
When "Please, Power off" displayed. Upgrade finished.
Don¡'t forget delete the upgrade file.
Important: DO NOT TURN OFF POWER when upgrading, otherwise DSONEi/mini will PERMANENT BROKEN.