DIY: - Replacing leaking Front Crank/Main Seal | BMW M5 ...
Removal steps: Undercarriage panels -> fan -> belts -> crank pulley -> harmonic dampener -> front main/crank seal. The beginning of the procedure is identical to changing the belts, you got to get the fan off, which there's plenty of DIY's for. I removed the undercarriage panels for better access; I think it's a must.