Return of the Jodi is a safe way to enable homebrew on a Wii without hardware modification. Return of the Jodi is achieved by playing a hacked game save for Lego Star Wars which executes a homebrew application from an external SD card. Examples of such homebrew .elf or .dol files can be found on the Homebrew applications page. The Return of the Jodi was created by Team Twiizers & roto.
This exploit works on the original Lego Star Wars game as well as the newer (1.01) release (NTSC and PAL) all through one masterfully crafted save.
Prerequisites
--------------
1.SD card (not SHDC) formatted as FAT16 or FAT32
2.Some possibility to copy the savegame from the PC to the SD card (i.e. card reader)
3.Lego Star Wars ;-) (you have to boot it at least once before)
4.Some homebrew software to load, e.g. the HackMii Installer. Although this isn't necessary, it's highly recommended ;-)
Howto
-----
1.(OPTIONAL) If you have an existing "Lego Star Wars" savegame. MOVE it to another SD CARD.
2.Copy the "private" directory from the Return of the Jodi download to the root of your SD card.
3.Take your homebrew and put it in the ROOT of your SD card as "boot.elf"
4.Put your SD card in your Wii and turn it on.
5.Go into Wii Options -> Data Management -> Save Data -> Wii.
6.Go to SD card and select the "Return of the Jodi" savegame that corresponds to your game region.
7.NOTE: Some people are having problems with the Wii not "seeing" the savegame on the SD card. If you are experiencing this, try setting the archive bit for the data.bin file. In Windows this can be either be done from the file's properties dialog (right click on it in Windows Explorer and check the box) or from the command line using "attrib +a
8.Copy the savegame to the Wii.
9.Boot Lego Star Wars.
10.Load the saved game you just copied to the Wii.
11.Go to the bar on the right and choose the character named "Return of Jodi".
News Source (1)(2)