If you’re interested enough to do a little leg-work there are buzzer control functions in the Pololu AVR C/C++ Library, as well as some discussions on playing music with the Orangutan X2 buzzer here (easily portable to the 3pi), including how to automatically decompile midi files into buzzer-playable note arrays in this post.
Considerations for storing large not arrays in flash memory rather than in RAM come up in this thread.
Good luck with the competition!
-Adam