Grim Fandango

First take the elevater to the bottom. Now position the forklift all the way right you can and make it face the exit.

You can check if it is in the right spot by pressing the red button and seeing if the little cut out on the metal screen door that shuts when the elevater is in use is right in front of the forklift.

If done correctly you should be able to press the red button then just turn around and enter the forklift. Shouldn't take to long. Also make sure that the fork is not up, there is a button on the left side of the forklift.

Now when the elevator is at the bottom, press the red button to start it, quickly turn around and jump into the forklift and keep pressing up.

If you did it right the forklift should jam it self into the secret level inbetween the two levels the lift goes to.

Now finally after this is all done just get out of the elevator, press the button on the forklift that raises or lowers the fork, its on the left side near the front, and then just walk on through.

Change your controls to camera-orientated. That way you don't have to turn all the way around, and can simply press down, enter and forward after pressing the button.