-----****What Is Gecko OS?****-----
well What Gecko os is, it is a loader with a built in Ocarina cheat device in it, which alows you to hack on your favorite games, play your back-ups and it also bypass's the Disc Update process so you could play your games like normal.
-----****How To Install...****-----
1. Download it from this link( http://geckodownloads.googlecode.com/files/gecko1931.zip )
2. navigate to HBC folder by going to Gecko1931 -> HBC
3.Drag that Gecko1931 Folder in the HBC folder to your apps folder so it should look like: sd:/apps/Gecko1931/boot.elf
meta.xml
icon.png
ok now for the codes:

download Cheat code converter, and Megacheatdownloader.this is a must because you can get the codes and convert them w/o a Pc

Make a folder called: codes and txtcodes in the root of your sd card.
get what codes you want from this site or others and put them into a text file.

Throw the txt file into txtcodes and run Cheatcode Manager (you can get it from Homebrew browser)
choose the txt file and choose the codes you want and press "1" to convert them into a gct file.
now run gecko os and go to configuration.
dont forget to change the hooks to OSsleeperthread, turn Sd codes "ON" and to Turn Debug menu "ON".
Run the game and it will load the codes