Left side front pocket. There is a spot in the upper right hand corner already made for it. You will see the markings on the plastic. Don't know if it's a knock out or if you have to drill. I had mine put in by the dealer when I bought my bike in 09.
Then I drilled a hole in the lid, screwed over the hole a marine waterproof plug with a plastic cap on top and I fish the wires for my GPS and iPod out the opening. If it rains I just push wires back in and close cap. Did not want to notch out the door and take a chance on pinching the wire(s).
Just like 2 wheel wing said it is mounted in the left front pocket. You do have to dirll a 7/8" (I believe) hole in the right front coner. It is marked. It is also plug-and-play. You have to take the pocket out to see where to plug it in. There is a red plug under the pocket. I believe that Wingstuff has the best deal on them (about $10). I bought 2 of them because the shipping was the same as for one.
One word of caution. It is ok to charge a phone or something that pulls 5A or less with an outlet made to plug in under the pocket, but if you want to power something that takes more juice like an air compressor then you need to run straight off the battery and wire a 15A or so fuse into it. I put one in trunk for this purpose. The trunk also has a plug-and-play outlet to plug into but I ran under the seat and to the battery.
When I hooked up my power plug for my GPS I left the connector plug under the pocket so I didn't have to cut the pocket out or take up the space in the pocket with the plug, then you can run the small end of the charger that hooks up to your device through the same hole the AUX cable comes through.
I bought my OEM lighter socket from Wingstuff and easily installed it myself. The left fairing pocket is marked where you'll drill the hole and the electrical connector for it is tucked away inside a rubber boot just under the pocket (large hands are not beneficial when accessing/locating this connector). Other than that, it's a piece of cake!
I did however have to ask how to remove the pins that hold the pocket in place for fear of breaking something (simply depress the center pin in the retainer and the retainer comes right out. To reinstall, push the center pin back up to the raised position, drop it in the hole, then push the center pin back down til it's flush).