This one's fairly simple guys. I adjusted mine a bit last time I had my interior apart.
1: Get in your trunk, face the rear of the car.
2. Take your philips screwdriver and remove the 7 screws (well, was 7 when the factory put it there) on the panel between the two really big panels that wrap around your interior. Remove panel.
3. Take a wrench (forget which size, likely 10mm) and tighten the slack on the cable release a bit. There are two releases, one for the key, the other for the lever, tighten them both up a bit if you can't figure out which goes to what.
4. Test lever. Put panel back on when you get it working, done.
Simple, yes?