Lift the left I/O frame up and out of the computer. Pay attention to the thin metal EMI fingers, as they may catch as you remove the left I/O frame.

The speaker wire may be hooked onto the I/O frame. Lift it out of the catch and don't forget to put it back when you are reversing the procedure.

The part of the shield you are removing is attached to other part by little hooks underneath that are hard to see until you have it apart. They're located over the headphone jack and the firewire port.