Bring the seven core cable through the floor and into the boot. Separate the wires, connect the white to a good earth point, take the yellow and the black to the nearside and the others to the off side. Locate the n/s indicator and connect the yellow wire to the indicator lead. The black wire goes to the n/s side light. The green wire goes to the o/s indicator, the brown wire to the o/s side light and the red wire to the brake light. The blue goes to the fog light. All the connections can be done with Scotchlocs. You also need a wire from each indicator to a buzzer. You may also have a plug connector in the boot. In which case a Citroen dealer can sell you a plugin towing loom. Had your Saxo been fitted with multiplexed wiring, it would have been safer to put all the connections through a seven way bypass relay.