Well, the Vehicle-Specific install section on that website is somewhat lacking, but the concept is the same. You pretty much got the idea straight:
1)
Unhook the negative battery terminal from the battery (this is for safety reasons while working on your car).
2)
Run a Power wire from the positive battery terminal, through your firewall, and into the trunk. Usually, this is the hardest part, and the reason why is because it's hard to run the power wire from the engine bay into the car. I myself drilled a hole in the firewall (behind the glove compartment), used a grommet like
this so the firewall metal wont cut into the power wire over time (very important to use the grommet), then ran the wire in. Many people do what you said and run the power wire through the factory grommet instead of drilling a hole, but I always find drilling a hole much easier, less time consuming, and allows you to run ANY size wire you want. To tell you the truth, the best way to find out how to do this for your vehicle is to find some Camry forums and ask there. You can try asking on these forums, but it's pretty hard to find installation tips for
specific vehicles. If you do decide to drill a hole, double check, then triple check that where ever you drill the hole, there aren't any fuel lines, electrical lines, or anything else that you might accidentally drill into.
Now, once the power wire has been run into the cabin of the car, you can usually run the wire under some of the factory plastic panels which are by the door, or you can run it under the carpet. Usually, most people run the wires under the factory plastic pieces. Look at this
thread: this is for a 2008 Altima sedan, but the concept is the same. You should be able to remove the plastic panels, or simply tuck the wire beneath it. I have a 2008 Altima myself, and I just tucked the power wire under the plastic trim pieces instead of actually removing them - it's worked perfectly fine for the past 2 years.
Running the power wire into the trunk is easy - just run it under the back seat into the trunk. Usually, the back seat of new cars can be removed, so you can run the power wire under the seat and into the trunk to your amp.
Don't forget the in-line fuse, which should be ~1ft-2ft away from the battery in the power cable, depending on your own install. Match this fuse to the ampacity of the cable if the amplifier has its own integral fuses.
3)
Run the signal wires from your head unit to your amp. You're right in that the signal wires should be run on the opposite side of the vehicle that the power wire is ran. This is to prevent interference. Since you want to keep your factory head unit, you need to use what is known as a Line Output Converter (LOC) if you DON'T have RCA outputs.
This website has some of the best LOC's on the market, and they're not very expensive (Or you can use any other brand such as Scosche, or the line-level inputs on your amplifier if it has them). You will want the "N-RHL2," which is the 2 channel version since you're only running a subwoofer amp. Basically, you will tap into your front or rear speakers (your choice, as long as it's left and right), then run a set of RCA's from the LOC to the amplifier. You don't HAVE to remove the head unit to do this. If your rear speakers are mounted on the rear deck, you can to what I did: tap into the speaker wires that go to the rear speakers in the trunk, since those wires are easily accessible. I used
these wire taps from Radio Shack. If you don't have rear deck speakers, you're going to have to remove the headunit to tap into the speaker wires. If your factory head unit DOES have RCA outputs, you can simply run RCA cables from the head unit straight to the amp instead of using an LOC. The best way to find out if your head unit has these outputs, besides actually taking it out to look for yourself, is to ask on some Camry forums.
4)
Ground the amplifier by running a wire from the amp to a nearby bolt that goes directly into the car's chassis. You want to make sure the ground wire is going into bare metal, so if there's paint or something, you'll need to sand it off for a good connection.
5)
Run a remote turn on wire to your amplifier. The best way to do this is to run a wire from the Remote/Trigger wire from the LOC I linked to above to the remote wire input on your amplifier. But this is, of course, if you're using a headunit that doesn't have a dedicated remote wire. You can also use any 12v source, but you want it to be a 12v source that turns on and off with your car. I used
this to tap into my 12v accessory fuse since I didn't use that LOC (I used a different one that didn't include a Remote wire).
6) R
un speaker wires from amp to sub. Pretty self explanatory, use the subwoofer wiring on the 12 volt website to help you out with this.
