[JWA]

There's a spare switched circuit in the fuse block under the dash. Lots of documentation here.

For power, I had good luck mounting a USB port in the small panel to the right of the steering wheel column down inside of the trinket tray in my old Elise. A friend of mine installed a power port in the front by buying one of the switch panels for cars with driving lights and mounted the power port in the new extra light switch opening.

 

[JWA]

This thread shows the general process: http://www.lotustalk.com/forums/f133/adding-12v-lighter-outlet-79356/.

I thought that tesprit posted pics of his solution but I couldn't find them. I emailed him to ask if he knows where they are.