There are yellow plugs under each seat. You'll need to stick a resistor in them when you take the seats out. I can't recall the exact resistance, but a quick search should turn that up.
The gauge pack requires a lot of wiring that is not included in the car. About the only thing you get out of the clock area is switched power and ground. This should give you a good idea of what is involved in a typical gauge install. It's not tough to do. It's just time-consuming.