The way yunni has done it is easier, but i'll show you my way as well.

about 1m of 2 core wire on each side then connected them into the main light (the orange/blue and black/blue connections)



I'll have to get some proper measurements up tomorrow (iirc the lights are about the size of a debit car)


However, you do need to cut away at the metal behind as they simply don't fit otherwise. (one of the sides is more fiddly/require more metal to be cut to accommodate the connector/plug going to the light)