How long does a police officer have to go to school to work as part time?

In most locations you are required to be certified by the state in order to have the sworn the powers of a law enforcement officer. This would include, classroom time, physical training, etc, etc. This is mainly due to the trainiing involved and liability issues for the hiring agency. Requirements for 'part-time' officers may vary slightly. You would have to contact the particular agency involved to ascertain this information.