1. Zero the tone control(s) of the guitar
2. Use the boost switch on the G2M to match the output signal of the guitar to the input sensitivity of the G2M (pluck each string and watch the "level" LED)
2. Make sure the pitchbend parameter of the midi module being used is set to +/- 2 semitones
Make sure you know: that the G2M is monophonic, not polyphonic, you cannot play chords with it.