Since ZSR Forums have been messed up for awhile and were even down at one point I figured it'd probably be good to copy this post here.

If you want fast and efficient practice on VC you can download these gecko codes here. Simply drop this file in the "codes" folder on your SD card. To get Gecko on your wii, download gecko here then take the folder named "Gecko 1931" from the zip file you downloaded and copy it to the "Apps" folder on your SD card. There should be a gecko icon on homebrew which you can use to boot up gecko. On gecko go to launch channel, select oot and it should boot the codes automatically.

A nice summary of the button conditional codes can be found here (credit goes to scaramanga for making this).

• d-pad left to save location 1, R+d-pad left to save location 2. d-pad right to teleport to saved location 1, R+d-pad right to saved location 2.
• Wrong warp. This code works by allowing you to modify your rupee count which decides your location, the list of locations is here. Once you've set your rupee count (L+dpad up to increase L+dpad down to decrease) to the location you want to go to, you simply walk through a loading zone (or use R+L+dpad down to kill yourself) and hold L+A.
• Reload area. Press L+R+A+B to reload the area you're in. This can be combined with the wrong warp code to instantly wrong warp you from wherever you are.
• Soft reset. Press start+L+R+A+B to activate.
• Save which flags you have triggered by pressing L+R+d-pad left and then load the saved flags by pressing L+R+d-pad right. When you reload the flags the effect usually only takes place after you've passed through a loading zone so you must re-enter the room for the flags to be set back to their initial state (switches you step on are an exception to this, there may be others). If you simply load flags without saving them you will set the flags back to their default value so if your file has already beaten a certain boss you can simply load flags and that boss will no longer be defeated. You can also only load flags in the room you saved them in so if you save the flags in deku tree before breaking the web then you must also load them in deku tree for the web to reappear. Not all flags get saved, I don't think cutscene flags are saved but most flags useful for practice are saved like which webs have been burnt, which rupees you've collected in kokiri forest etc.
• d-pad up to levitate.
• d-pad down for a huge speedboost.
• A+B+R to fall through the floor (useful for escaping cutscenes)
• R+dpad up to toggle between being adult Link and child Link. The effect only occurs once you pass through a loading zone. The default is set to adult Link so when you first pass through a loading zone, you will always change to adult unless you press R+dpad up.
• R + L + d-pad down to die (only works when infinite health has been toggled off).
• d-pad down + R to die to toggle between having infinite health and having half a heart

Here are some codes which don't involve button conditionals:

• The tower collapse timer is frozen.
• Able to equip all c-items (for instance megaton hammer as child).
• Able to use c-items anywhere (set farore's wind outside of a temple for example).
• Infinite ammo, magic and small keys.
• Ammo + wallet upgrades and gold scale.
• Some inventory (like farore's wind, ocarina, hookshot etc.).
• All songs, stones and medallions.

These codes only work on the Japanese 1.2 version of oot and the codes with button conditionals (like teleporting and levitating etc.) only work with the gamecube controller (or N64 controller if you have an N64 to gamecube adapter) and will not work with the classic controller. Thanks to everyone in the forum for pointing out various problems and providing solutions! If anyone has any requests for other cheat codes please let me know. The text file for anyone who wants to improve / make adjustments is here.

Troubleshooting:

If you have installed gecko but the launch channel option does not appear it is because you need to patch IOS36 with simple IOS patcher. If your wii is not connected to the internet it will complain that it can't find the patched ios to install. Instead, you have to download the ios (here) and place it onto your sd card before running the installer. If you launch the game and it says codes booting yet none of the codes work, it is probably because you have the wrong hook type. Go to config options and set the gecko hook type to default.