I can't provide detailed links, but in general, this is how you can route the cable: from the stereo, pass the wires behind the passenger side airbag cover (not sure if your Elise has that or not, but there should be a space there). On the passenger side of the extruded aluminum storage tray portion of the dash, there's a flat plastic cover. Pop that off. You can then get to the cables that you ran through the dash, and reroute them towards the front of the car, into the space above the passenger's feet. From there, you can route them to the centerline of the vehicle, and drop them down into the aluminum tunnel that divides the footwells. Then through the center console, to the firewall grommet behind the driver's seat, then back to the trunk via the grommet the battery wires pass through.
