I ordered these LED strips on amazon. They are self powered using 4 AAA batteries and have a motion sensor built in that only activates in low light conditions.
They come with a magnetic strip that fits perfectly underneath the trunk cover. I placed them on the left and right sides right underneath the plastic supports that hold the trunk cover. It's a perfect fit.
So you just insert the batteries, attach the magnetic strip and voilà - instant trunk lighting without all the hassle of finding the right wires and possibly messing something up : )