Step 1: Make sure that you clipped the small white piece of plastic retaining the wires between the two bosses/standoffs. The piece of plastic is highlighted in the image in Step 4. With the wires more accessible, follow the wires from the Shout It switch to the main circuit board (not the little one with the Shout It button on it) and snip them off near the main circuit board. Strip the ends of the long wires that now lead to the switch but are no longer connected to the main circuit board.
Step 2: Tighten the audio jack into the half-hole that you've just drilled in the body of the Bop It.
Step 3: Cut the wire leading from the main circuit board to the bottom of the speaker (cut it about in half). Strip both ends.
Step 4: Create your first junction. This junction should connect the following wires:
1) Signal wire coming from the board (the one you just snipped that led to the bottom of the speaker)
2) One of the wires from the Shout It switch
3) A wire leading from the resistor which is attached to the audio tab of the audio jack (you'll need to add this wire and resistor). Audio Tab --> Resistor --> Wire --> Junction (resistor not shown in first picture, my apologies, but you can see it in the second picture).
Step 5: Create your second junction: This junction should connect the following wires:
1) Unused Shout It wire (the one not used for Junction 1 in step 4)
2) Signal wire leading from bottom of primary speaker
Step 6: Cut the wire leading from the top of the primary speaker to the main circuit board. This is the ground wire for the primary speaker and you will need to splice the ground from the audio jack into it. Strip the ends of the wire after you have clipped it.
Step 7: Create your third junction: This junction should connect the following wires:
1 and 2) The two ends of the the primary speaker ground wire from Step 6.
3) A wire leading from the ground tab of the audio jack (you'll need to add this wire).
You may choose to insulate each of your junctions with electrical tape or hot glue. I did not because nothing was near anything else. It's up to you.