Pin 3 of the lemo is both the audio input at microphone level and the bias voltage for the microphone.
For most Sennheiser microphones (e.g. MKE2, HSP2, HS2, etc.) this requires the red wire to be soldered to pin 3 of the lemo and the blue wire to be soldered to pin 1 of the lemo.
The screen is folded back into the barrel of the connector.
To connect a standard dynamic microphone with a 3 pin XLR connector, you will need to make a special lead:
Pin 2 is generally unused for connecting Sennheiser microphones.