Instructions
Remove the memory card from your Nintendo DS and insert it into your computer's card reader.
Open a web browser and go to the "R4" website (see References link). Click on the "R4 DS Kernel" download icon to download the software.
Wait for the software to download and then open the software. Click on the "Start" button and then click on the "Computer" icon from the menu.
Click on your memory card to open the window. Drag the R4 software from your computer to the memory card icon to transfer the software to the memory card.
Remove the memory card from your computer and then reinsert it into your Nintendo DS. Boot the Nintendo DS to load the new firmware.