what is the best and easiest way to do this and to know it has def been done?

 

Are you talking about a classic (GC/GF) or newage/hatchback?

 

sorry mate classic

 

In which case the best way to do it is to connect the black and green plugs under the dash, drive the car slowly and wait until the check engine light either flashes an even on-off-on-off blinking pattern (which means okay) or starts flashing out numerical error codes.