Flanked by Suffolk County Police Commissioner John Gallagher and representatives of local radio stations, Rep. Felix Grucci yesterday proposed that Long Island adopt a system used in some other states in which radio and television stations broadcast emergency alerts about children who have been abducted.  He detailed a system that could help law enforcement agencies move quickly to recover abducted children.  In those areas where the plan is implemented, local radio and television stations agree to interrupt their programming when notified by police that a child has been abducted and is likely to be in danger.  The alerts are similar to the well-established Emergency Broadcast System.  The system is similar to systems employed in various communities in 11 other states, America's Missing Broadcast Emergency Response, known as the AMBER Plan, has been an effective tool in locating missing children, Grucci said.  The program began six years ago after the abduction and murder of a 9 year old Texas girl, Amber Hagerman.