The best power source is the back of the cigarette lighter. That will involve lifting the centre console cup-holder out, then the console itself. There are directions on this site that will assist you. The only alternative I have used is to remove the steering column covers and take power from the ignition switch leads. The wires are tiny and you sometimes have to splice extra wire in for this. Put fuses on everything, rather than risk a short in your wires or equipment from stuffing up something else already fitted in the car or worse, your ECU! Make sure also you don't fit so much kit all taking power off the cigarette lighter that you run that circuit too hot!
CP_e Standback & PNP; CP_e 3" SS Downpipe; Corksport FMIC with Top-mount K&N filter & OEM Ram CAI; Turbosmart BOV; Dashhawk; Prosport Boost Guage; JBR solid shift bushes; DBA 4000 Wiper-Slot front rotors; Hawk Ferro-Carbon HPS Street front brake pads (@ 69,000km); Sumitomo HTRZIII's in 225/45 x 18