One of those tutorials if for converting to codebreaker format.
To convert cheats I suggest crackers GBACCC: http://min.midco.net/cracker/ This site also has loads of cheating tools including the somewhat hard to find AR Crypt.rar and CBAcrypt.rar which are used for decoding cheats to a more useable format. CCCGP.rar is for patching in Game Genie codes to roms although it is mainly for older systems as nobody really made any game genie cheats for the GBA.
Anyhow do you want to cheat in an emulator or on a flashcard or using a real action replay on games?
If it is the former those guides both use VBA which is great for GBA roms.
If you want a flashcard and your cart does do cheats well (most have fair support) then try and use that.
On a cart without (decent) cheat support I suggest GABsharky: http://gathering.tweakers.net/forum/list_messages/942567/26 Click on Stevens Cheating guide and you will have a nice guide to from start to finish.
Also check out some of the lists that come with stuff the like m3 and EZFlash cards and GBAlink ( http://www.gbalink.net/ ), those libraries are huge and are usually unencrypted with guides to how they work.