All of my power wires go through the hole on the drivers side where the rubber boot is. I don't have any pics, it's a hard spot to photograph. You'll see it easier from the engine compartment. If you push the boot over a little at the edge you'll see where you can push a wire through.
i did mine on the passenger side throught the hole that the A/C drip hose (not sure what to call it) goes through... bit it comes out under dash on passenger side and goes through floorboard and has hole drilled and grommet already there.. i just pull the A/c hoes out ran my wire for my amp through it the stuck the a/c hose back through. and it fit nicely.. and i got a 4 gauge wire.