Regarding the show of 3-12-11 and the woman with a leaky trunk who wanted to drill a hole in her spare tire well.
I have an 02 Chevy Cavalier with the same problem. I do admit her proposed solution did cross my mind. What worked for me was tightening the nuts attaching the trunk to the body. AND, the seal had gone bad and was letting water in around there. I used silicon caulking for bathrooms around the edge of the seal to stop water from getting in.