Install devkitpro's devkitARM, the devkitarm-rules and devkitarm-crtls
files, and set up the environment variables DEVKITARM and PATH properly.
After that, arm-none-eabi* should resolve to the tools in this kit
with the proper files in place, not the one in the system.
If all goes well:
% make && vba *.gba
Have fun!