Thank You very much! I've just made a tool to fix checksum in gen 1-2-3.
I know that it's not very useful, but I'm doing my own pokemon editor (Only first gen editor is completed )
You have to load the save from the emulator. John GBA use savestates Like checkpoints so You have to load manually the save. Press Load ROM from the Emulator's Menu, choose pokemon fire red version and select the save. Let me know