I have a habit of being very long winded... If these instructions aren't enough just lemme know and I'll elaborate later...
Here's how you can run wire under the big black plastic things that run along the rear-edge of the hood. I'm going to call these plastic pieces "windshield trim".
You wont need any special tools to do this. It took me somewhere in the neighborhood of 2 hours, but I didn't know what I was doing and I also had to stop to take pictures.
Take the glove box out.
Remove the windshield wipers (there's a single 12mm nut per wiper; just unscrew and jimmy them loose). You may want to mark/note how the wipers are positioned before removing them (a dry-erase marker would be good for this).
The windshield trim is held on with 2 screws (under black plastic caps) and by the long rubber weather-seal. The wiper fluid lines are attached to the windshield trim. I suppose it's probably possible to completely remove the fluid lines but I did not find it to be necessary.
Take the screws out first, then pop the hood. Find the rubber seal (you can't miss it). You'll need to gently pull the seal off a bunch of blue cleats that look like this...
I found stretching the seal to release one side of the cleat then the other worked well.
With the screws taken out and the seal removed you pretty much just need to pull to get the windshield trim off. Like a lot of the pieces on this car you just need to be careful. The trim comes off horizontally (toward the front of the car) for the most part.
Set the trim aside.
Under the windshield trim there is another plastic thing, I'm going to call this one the "runoff duct". It is held on by 3 round detachable anchors and 3 clips. To get the detachable anchors off you need to unscrew the center part 1/2 turn, pull the center up, then pull the whole anchor out.
Take out the anchors, unhook the clips, then pull out the runoff duct and set it aside.
Look for the big bunch of wires coming through the firewall behind where the glove compartment was. There is a big rubber grommet there that we are going to run the power wire through.
There is a little nub near the top of the grommet. Use some long needle nose pliers to pull the tip of the nub to the inside of the car.
Use the pliers and some wire cutters to cut the end of the nub off. Push the nub back to the engine side. You're left with a hole to the outside world...
Now thread the wire through the nub thing. I put a little soapy water on the end of the wire to get it started. Pull enough through so the other end will reach the battery.
Next cut a small hole in this grommet and pull the wire through.
Like so...
I put a cable protector on and zip tied the cable to this metal thing. There might be more you could do here, but I think this'll be sufficient.
Now you can pretty much put all the pieces back on. On the battery side I had to cut a small part of the windshield trim off to get the cable through. I put on some more cable protector to protect against the sharp plastic.
<<I'll put a pic of this up soon...>>
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The way I see it, this is a perfect place to get the wire from the battery to the passenger-side firewall grommet. It's pretty far from the heat of the turbo plus the install is pretty easy and straightforward.
One slight downside could be that where the power cable comes out is right next to the main ground wire of the car. But so-long-as the power cable is fused close to the battery I don't this is a real concern.
