1. open the drivers side door
2. pop plastic panel off the end of the dashboard with your finger
3. look at firewall - there is a hole there filled with expanding foam
4. run a long screwdriver through it, making a channel to the engine compartment
5. fish your wires from the engine area (actually it's the fender) to the interior
6. when done, squeeze a little sealent in to fill the void
7. pop the plastic panel back on
So easy, even *I* can do it ...