There should be a whole in the side of the firewall structure way up above the fuse panel on the drivers side this whole in turn comes out way back in the corner of the fender on that side. There is should be one rather large whole with a rubber plug in it. The best way to find it is to pull the fender skirt out some and run your hand back towards the door. You should be able to see/feel the wiring from the main fuse box under the hood where. The empty hole is just above where those wires go in. That's how it is on my 98GT anyway.