The developers of the littleBits Korg Synth Kit have added documentation at their site that explains how you can use the Kit to process audio from a guitar, voice or other instruments.

To connect your instrument to the Synth Kit, you will need:

• littleBits Synth Kit
• An instrument with an output jack
• The littleBits microphone module
• An 1/8″ audio cable to connect your instrument to the microphone module.
• An amplifier or a ¼” to 1/8″ cable

In a nutshell, plug your instrument into an amp and then use the 1/4″ to 1/8″ cable to connect the output to the audio input on the littleBits microphone module.

Here’s a demo of this in action:

See the littleBits site for details.