if all you want is the voice nav/mic, then all you have to do is connect a few wires to your amp (runs some wires from NAV to amp). To get the BT to work, you will have to purchase a mic and connect it (wire from NAV it to your mic).
Lots of thread regarding how to do this.
Anyway:
I wanted to get the iSimple product but decided against it because:
1) buggy/laggy
2) BT only works when unit is on (read: if you are listening to your radio, the call will not go through the speakers unless you turn it on............ pain in the a##)