Patch the relevant DS Download Station ROM so that it will send wooddumper over Download Play, using dspatch or dspatch-gui.
Put the ROM on your DSi/3DS SD card
Follow the relevant guide as far as needed: DSi guide, 3DS guide in order to run the the patched Download Station ROM (or you can follow the whole thing to make using homebrew more convenient)
Put wooddumper in the relevant folder * Follow the relevant guide as far as needed in order to run wii-ds-rom-sender: [todo] (or you can follow the whole thing to make using homebrew more convenient)
PC
Follow this guide in order to send wooddumper over Download Play. Requires Windows XP and a compatible Wi-Fi card.