Hi,
I'm new here but I came across and bought one of these NDS ADAPTER BACKUP SAVE GAMES NINTENDO DS LITE.
It wasn't what I was looking for but I think that Nathan576 may be able to use it for what he wants, I'm not 100% sure because it wasn't what I was after.
I was hoping that it would allow me to read my NDS original cards so that I could copy them to my N5 cart.
This is the information about the adapter;
Backup your Nintendo DS saved games to your PC, or download new saves and write them to the cartridges with the NDS Adapter. You'll be able to store your precious saves from your original games on your PC or share them with friends.
Simply plug the NDS adapter into a spare USB port on your PC, install the drivers on the included CD and plug any DS cartridge into the NDS Adaptor. The plug and play, drag and drop interface is a breeze to use and will have you backing up your saved games in no time at all. You can also download saves from the internet and write them to your original retail cartridges.
I found it on eBay, I hope that is of some help.