How do you install serpentine belt on a 540 BMW?

To install the serpentine belt on a BMW 540, first, ensure the engine is off and cool. Locate the belt routing diagram, usually found on a sticker in the engine bay, to understand the correct path. Using a wrench or ratchet, relieve tension on the tensioner pulley, then slide the new belt over the pulleys according to the diagram. Finally, release the tensioner to secure the belt in place and double-check that it is properly aligned on all pulleys.