There's a work-around for this. Grab VisualBoyAdvance for your PC. Grab your save from your sd card ("gametitle".sav), put it in the same directory as the game on your PC, and change the extension from ".sav" to ".sa1" (obviously without the quotes.
Next step is to start the emulator on your PC, load up the game you want to insert code into, then hit file > Import > Battery File...
Select your .sa1 file, now you are playing the same game you are on your phone. VisualBoyAdvance has the ability to do Gameshark codes and Codebreaker codes. So insert whatever codes you like, save your game, rename the savefile back to having an extension with a .sav ending, and put the file back in the same directory as the game (on your phone).
Tada!