Yes, it can be done. You’d need to implement a serial communication interface between the Lumazoid and another Arduino. The Lumazoid is really just an Arduino Uno. The 6-pin connector at the top of the Lumazoid board is for serial programming with an FTDI adapter if you want to change the code on it. The pinout is standard, just google for “FTDI pinout”.
So a solution could be built where the Lumazoid listens for serial input occasionally (this would interrupt the constant reading of the audio input). The Lumazoid could also write to serial telling you what mode it’s in.
Probably a simpler approach is to use the A2 and A3 pins that are broken out to pads. You could use one for additional input, giving different analog values that have different meanings.
I guess it’s not that easy… 🙂