How do you change the alternator belt on a peugeot 307 16tdi?

To change the alternator belt on a Peugeot 307 1.6 HDi, start by disconnecting the battery for safety. Remove the engine cover and locate the alternator; then, use a wrench to loosen the tensioner pulley and relieve tension on the belt. Slide the old belt off and replace it with the new one, ensuring it follows the correct routing. Finally, re-tension the belt, reattach the engine cover, and reconnect the battery.