An ASL Airlines France Boeing 737-400 freighter, registration F-GZTJ performing freight flight 5O-773 from Marseille to Ajaccio (France), was climbing out of Marseille when the crew reported an odour and smoke in the cockpit. The crew stopped the climb at about FL110 and returned to Marseille for a safe landing about 15 minutes after departure. A replacement Boeing 737-400 registration F-GZTI reached Ajaccio with a delay of about 2.5 hours. The occurrence aircraft remained on the ground for about 20 hours, then resumed service.