The Gameboy Advance emulator for PSP based on gPSP and gPSP kai source code has been updated by the anonymous Japanese coder.
gpSP-J 110507 signed flofrucht.
(1)Copy the extracted PSP folder to your PSP root and overwrite existing files.
(2)Put the gba_bios.bin file in the same folder as the eboot of gpSP-J 110507.
(3)Put your roms in the /roms folder that is in the same folder as the eboot of gpSP-J 110507.
(4)Launch gpSP-J 110507 via XMB and have fun playing your roms.
Note: I don't provide the BIOS file, you need to download it. Just google it.