A police inspector shared the stage with herman's Hermits on Saturday night in a futile attempt to calm 9,000 hysterical youngsters attending a rock'n' roll orgy at Maple Leaf Stadium.     Inspector Richard Lewis, who headed a detachment of 60 policemen and policewomen, walked onto the stage after the Hermits had completed a number and took the microphone from Herman, the group's leader.     He began to speak but was drowned out for several minutes by a raging chorus of boos and hisses by the frantic fans. Finally the booing died down and the harried police inspector pleaded for order.     Struggling policement posted at the foot of the temporary stage and in the aisles had trouble controlling the swarms of screaming young girls trying to reach the performers.     The hysteria was fanned by groups who appeared in the show, including the Spastiks,, the Five Rogues, the Three and a Half and the Animals, who shared top billing with Herman's Hermits.     The action started before the show began as

Inspector Lewis was briefing his formidable platoon of officers. A group of young gatecrashers broke into the stadium through a storage room window and raced up a ramp leading into the grandstand.     The inspector ordered them to stop, but the youngsters scampered to the top of the ramp and disappeared.     Earlier, two boys snatched three $4.50 tickets from a woman and her two daughters. Police later tracked down the boys and questioned them in the manager's office.     The hysterical excercise was sparked by the solo singer of the Five Rogues, who took off his white tie, told the screaming girls it was his soul and tossed it into the audience.     Then the crowd erupted in roars of delight as the Animals were driven onto the field in two cars. As the group performed, girls raced down the aisles to give notes to the Animals' lead singer, Eric Burdon.     Several screeching girls had to be taken from the stadium while Burdon was singing and later during the performance of Herman and his Hermits.