My dealer has been unable to provide me with the necessary wiring information for me to install a trailer hitch wiring harness on my 2000 V70XC. I'd like to use a harness like the one shown here (or the 10-amp version of the same):

http://www.hitch-web.com/vhitch.asp?Veh_Type=Car&VehNo=14130&Class=CL2&bumper=None#t_one

The kit includes a long fused wire to supply power directly from the battery (so as not to place any significant load the circuits for the lights) to a relay box which has wires to splice to the car's lighting wires to tell the relay when the various lights are on or off.

1. Which wires do I want to splice to, or where do I find an index to the color coding of the wires? -- OR --

2. The rear bulb housing units have unoccupied spade terminals sticking out. Are these there, by any chance, to provide convenient connection points to the tail, turn, and brake light circuits?

3. What's the best/easiest/safest way to route the power wire from the battery? -- OR --

4. Was Volvo nice enough to provide an available power wire to the rear of the car for trailer wiring purposes? --OR --

5. Is there some easier way or provided connector already in the car that I don't know about?

TIA.