I properly wired the Scangauge today. (It is mounted in the front console right below the heated seat switches.
Exploring the web showed that the little rubber tray in the front console is removed by lifting it up at the front with the tape wrapped screwdriver. recommended for all trim work. (I used the screwdriver blade of a Swiss Army Knife as it is polished and has no sharp edges.) Once the tray is removed there are two rectangular holes in the back of the panel that holds the accessory power outlet. (See pix below from TreyP) I made one of the holes a little taller and slid the wire for the scangauge through it and then reinstalled the tray. The panel next to the gas pedal also needed to be removed to fish the wire. It all took less then 30 min.