I don't have pics but it's easy. I popped that grommet out and made a hole with a razor, then re installed it. I would run 0 gage and maybe a 4 gage for future expansion while your there. You'll always want to go bigger.
I had my arc xd1000.1 hooked up off the fuse box post and had no trouble. When I scrapped the bose and added an xd805 for the doors I ran a larger new cable to the battery post.
In order to run straight to the batt post I had to use an extended post w/aux post and a spacer. This was only $5 at the auto parts store.
The reason you go straight to the battery is for capacitance, because your electrical system has none. Think of your battery as mass storage of power. If you think of it like a water tank as the battery and a hose coming from it as a wire, perhaps it'll make it easy to put in perspective. If you had a device like a syringe on the end of the hose and tried to yank a gallon out of it very abruptly, you would suck the hose flat because it couldn't keep up, and wouldn't likely get your gallon out of it....however, if you did this directly at the tank....no problem. Always put any big power robbing accessories straight to the battery, and never anywhere else, INCLUDING the alternator. <----good way to fuck up an alternator.:cheers1: