Do you want to mute the music and speak, or have the music volume turn down but still play in the back ground? What kind of receiver are you using?
You're going to need to amplify the signal of that mic somehow. A microphone takes the sound waves you speak into it, directs them into a diaphragm, and creates an output signal. Do you know what kind of mic you have? If its a condenser mic, then you will need to have an external power source on at all times to induce voltage across the capacitor in the mic.
Honestly, its probably easier and cheaper to pick up a cheap mixer for 40 bones at Radio Shack.
Say you wired the ipod up and used the switch to open the circuit from the ipod and close the circuit to the mic. You'd still want a pre-amp in between the mic and the receiver to regulate the signal from the mic, otherwise you're going to run into issues. The ipod has a "pre-amp" that controls EQ and volume from the wheel, but the mic has no such device that I know of. If you can't control the gain of the amplifier powering the mic, you run the risk of it sounding like garbage.
Furthermore, because the signal from the ipod is so small, you may have the volume cranked way up on the receiver to power it. So when you turn the mic on, with no way to regulate the signal coming from the mic, you could blow the ears off anyone listening with tons of that squealing / distortion type stuff. A cheap mixer will provide you with pre-amps and volume control of each signal coming into the mixer, plus it will allow you to fade the music and mic volume into each other.
Adam
