I'm sorry. I'm kinda slow to this technical stuff. I have the DS Roms for the Wii/DS. How do I perform the procedure?
Simply copy the ROM "DS Download Station – Volume 1" to your SD and rename it haxxstation.nds
Then start the DS ROM Sender while having usable DS software or GB/NES ROMs on the SD. The ROM sending app will make use of Download Station and exploit it. Your DS will first "download the Downloader" and then you can download arbitrary DS software.
But keep in mind: This is very, very limited. The RAM of the old DS is only 4MB. Everything that is bigger will not fit (you can't "stream" software with this – it has to fit into RAM completely in one shot). That means you will not be able to upload any full commercial title (DS cartridge ROMs start at 8MB and go up to 512MB). Special demo versions fit (they are designed like this). Many homebrew apps can be used with this – including NES and GB(C) emulators which come with the ROM sender.
That has practical use: It allows playing NES/GB on a stock Nintendo DS without a flashcart. Don't use it for huge games that absolutely need saving (Pokemon) since turning off the DS means losing all progress. All NES games will fit into RAM and most GB(C) games – some GBC games have 4MB+the emulator… means too big (very few GBC games have 8MB).