Method 1c: "Soft Mod" for Nintendo Game Boy Advance, GBA-SP, and GBA Micro
-Plug in your miniSD card to your miniSD->SD adapter (Typically included with miniSD), and insert the card into your SD card reader on your computer. Make note of the drive letter windows gives to the drive. (For example, mine is set to X:\.)
-Open "My Computer" on your desktop or start menu, and right click on your card drive. Click 'Format'. Choose FAT (not FAT32) Formatting and click OK.
-Download the newest EZ4 Kernel. (Official Update Thread) You'll need to extract the "ezfla_up.bin" file from this archive.
-Copy the EZ4 Kernel file, "ezfla_up.bin" to the root (top) directory of your miniSD card. Do not use the EZ4 Client to do this.
-Remove the miniSD card and insert into your EZFlash IV. Insert into your GBA.
-Hold the R trigger as you turn on your GBA. Hold the R button down until you see the kernel updating process begin. Do not turn the power off until the update process reaches 100%. It should reset by itself when finished.
-Reinsert your miniSD card to your computer, and delete the "ezfla_up.bin" file from the card.
-Download the EZ4Client software. Extract the .zip to any location.
-Open the EZ4 software, click 'Config', and change the "Send Path" to your miniSD Card's path. (e.g, "X:\GBA\")
-Click 'Open' to select your GBA file. (Note: I will not be providing links to these for obvious legal reasons.)
-Click 'Send' to write it to your card. It is necessary to move the roms/programs to the card in this manner so that EZ4 Client may patch it accordingly. Do not just drag and drop backups from your computer to the card. They will not work properly.
-Remove the miniSD card from your PC and insert it into your EZFlash IV cart, and insert the cart into your GBA.
-Power on the GBA! It will boot to your EZFlash IV menu. From there, just select the game or file you wish to play.
If you're having a problem or if the above steps do not work for you, visit their forum http://www.sosuke.com/ezflash/
copied form the EZFlash IV tutorial
http://ezflash.sosuke.com/wiki/index.php?t...ash_IV_Tutorial