This is actually Paul323F's method but I've just put my cable in place and taken some pictures as I did it.

1. pull back the arch lining as much as possible (or remove it completely, would make it easier still) on the passenger side of the car (same side as battery) and remove the mud flap.

You'll see a black plastic grommet about 1.5" in diameter filling a hole that leads into the sill. Take it out, but keep it somewhere safe for now.

This picture shows the location of the hole, I'd already gotten a bit of plastic tape through into the car to pull the cable.

[img]http://lh6.ggpht.com/_kmwYjBvt_Ac/TTHCNdq_gUI/AAAAAAAAAns/XtVGcDHoMtE/s720/IMG_2034.JPG[/img]

2. Open the bonnet, you'll see this big black plastic thing on the side of the bay just next to the coolant expansion tank and fuse box. This is where you poke the power cable through into the wing. There's quite a lot of room in there, so poke around until the cable goes though. You can see my cable already in place.

[img]http://lh3.ggpht.com/_kmwYjBvt_Ac/TTHCOapsskI/AAAAAAAAAoA/HC9mcdfgWGY/s720/IMG_2041.JPG[/img]

3. This is inside the car - you'll need to remove the kick plate and sill cover thing. This is the tricky bit though - the hole the cable will come up through is actually another hole. It's easiest to get something you can bend into a right angle to try and feed through the holes first, then take your power cable to that and pull it though. I used plastic strapping as it was lying by the car, and I could bend right angles into it. I fed it from the inside of the car to the outside, so it went down into the sill, and then basically wiggled it lots forwards towards the front of the car and it eventually poked out of the hole in the first picture

[img]http://lh4.ggpht.com/_kmwYjBvt_Ac/TTHCNSbZrdI/AAAAAAAAAnw/gJebDNBTE_0/s720/IMG_2035.JPG[/img]

[img]http://lh5.ggpht.com/_kmwYjBvt_Ac/TTHCNtZNhRI/AAAAAAAAAn0/aWHrAeCZJqs/s720/IMG_2036.JPG[/img]

Being plastic strapping its quite thin so its hard to see but it twists and disappears down into the hole.

4. Tape your power cable on and pull it through, from outside to in! But before you do that, cut a hole in that original plastic grommet just big enough for the power cable, and push it back over the cable. This is so once you've pulled all the cable into the car, you can push the grommet back into place, sealing the hole again.

[img]http://lh5.ggpht.com/_kmwYjBvt_Ac/TTHCN6xwTpI/AAAAAAAAAn4/p_8h72dvzRk/s720/IMG_2037.JPG[/img]

5. At this point, you'll probably have already noticed a many many years worth of mud and crap. Good idea to wash it out with the hose, you could have done this first but I didn't and eventually decided I should. So long as your plastic grommet is in place, this little bit of spraying water shouldn't be a problem.

[img]http://lh6.ggpht.com/_kmwYjBvt_Ac/TTHCOaVPePI/AAAAAAAAAn8/9qiEyLH_Xp8/s720/IMG_2040.JPG[/img]



All that is left now is to run the cable through the car to your amp/sub/whatever. I ran mine just under the carpet along side of the car where the trim holds it down. You could also run it under the carpet I think, but would require taking seats out / lifting more carpet up. Depends on the size of your cable. And that's it

Good idea!

Nice write up