Also did a similar conversion in the trunk (we call it a boot in Australia):
Removed the power from the rear of the trunk light before starting and let cool. A 5 watt incandescent bulb can actually give a nasty burn if it is hot!. Then removed the cover and bulb. Threaded the small connector through the rear of the Trunk Light assembly. Connected using the wedge connector provided in the kit. Tested to ensure the correct polarity. Needed to remove the wedge and re-insert in the opposite direction. All worked fine.
Replaced the cover as it will help to prevent the wedge from coming loose. Trunk Light is much brighter and more centrally placed. Yes I know it is crooked, but it is installed in a place that you cannot see. Next time I will pay more attention to the alignment. Additionally, If one 4x3 LED array is not enough light, you can join two and add more light without exceeding the original circuit load (5 watts original, 2 watts for each 4x3 LED Array).