1. The built-in low powered mic
2. A lapel mic (one attached to your collar, to better pick up your voice)
3. An iPod (or any mp3 player, phone, computer etc)
Step 1: What you need:
A 2-way switch (must have six connections on its underside)
A mono headphone socket
A bit of wire (I only used about 20cm/8in, but get a metre or a yard so you have plenty of spare)
Small phillips head screwdriver
Hot glue gun (or super-glue, or anything good for plastic).
Step 2: Opening the Case
Disconnect the magic yellow box from the shirt.
Remove the battery cover, and take out the batteries. This isn't really crucial, but it makes it lighter so it's easier to handle.
Turn the magic yellow box over, and remove the three screws. Remove the plastic panel.
Now, see the circuit board? Without damaging the wires, try and turn it over a bit so you can see its back.