connect 9200 to swich relay on for external floodlights?

Hi my Scantronic 9200 currently switches on a relay to light outside lights when the bells ring.The bells do not have sab's they just have a direct connection from the board via 12 volts to ring them and there are two of them in parallel back and front.Years ago i cut into the bells cable and again in parallel i connected the output to a mains(i think it was)relay.This had 240 supply to it and i brought the switched live from the outside lights in to it and back to the outside lights.When the alarm sounded the lights lit up.Could you tell me the proper way to do this as i am going to renew both 500w pir lights as they are rusty .They are a type that are if switched on and off quickly they remain on steady(from B&Q) At one time i would have supplied power to them on the outide walls then looped the live feed through a waterproof momentary contact switch and back to the live on the light so i could interrupt the power briefly in the garden so the lights would stay on.How would a proper installer do this please?