Firstly, http://www.carsound.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=3;t=000870 here's a writeup I did when these cars first came out, including pictures too. Now that I've done more, I have a few things to add.
Tachometer: Remove the one black plastic "screw" from the instrument cluster trim, and then remove the "insert" that the "screw" was in, and then remove the black frame around the cluster. You'll see a plug at the top of the cluster, with the wires going upward. Tach is the black wire that's all the way to the left.
TACH NOTE: Now that winter's here, I've had a few Camrys (but not Corollas) come back that won't successfully remote start when cold. The engine hits 2200 RPM when first started during the cold, and this triggers the over-rev protection sometimes. Just make sure your units overrev protection doesn't kick in too early. If it does, hold the gas just a tiny bit with your foot, and then reprogram tach at the same time.
DOOR TRIGGER NOTES: On all models, the RED / yellow in the driver's running board beats the delay, and accepts domelight supervision. The RED / white at the cluster, just to the right of the tach wire, beats the delay and accepts domelight supervision. The RED / white at the dash dimmer switch IS affected by the delay, and accepts domelight supervision. (But, only the upscale LE has factory domelight delay--the stripper models don't.)
DOMELIGHT SUPERVISION NOTES: Notice that the dash dimmer includes a position that disables the domelight altogether. You can choose to do your domelight supervision either before or after this switch. The RED / black from the switch will supervise the domelight ALL the time, whether your customer wants it or not. If you use any of the three door trigger locations mentioned above, your customer can still 100% disable all domelight activity by moving this switch to "off."
All of the domelight wires mentioned are high-current; you'll have to use a relay to power them. I even found the wire coming from just the driver's doorpin switch, but this is high-current too.
The Corolla LE (the one with woodgrain) has factory domelight supervision, which comes on when the correct unlock wire is energized. However, it isn't going to come on when the engine is running under remote start, so you may want to add your own aftermarket supervision anyway.
PARKING AND BRAKE WIRES: The + parking light wire (green) can be found at the dash dimmer switch, or in the driver's running board. The GREEN / WHITE brake wire is in the running board too.
If doing remote start, or alarm/remote start combo, I think it makes sense to bundle your door trigger/park/brake wires together, and run them all to the driver's running board for a simple install. On the other hand, if you're doing alarm-only on a stripper model, bundle the door trigger/parklamp wires together, and run them both to the dimmer switch and attach there.
REMOTE START NOTE: The BLACK / YELLOW second accessory wire powers up the climate controls. The blue/red accessory wire does the radio, and is not necessary for remote start. Also, the white constant wire is tiny---I always tie all my constant wires into the car's big black constant wire.
DOOR LOCK NOTES: The green wire in either kick panel, which tests off the door key cylinder, will lock the doors. If you want two-step unlocking, use the blue / YELLOW in the driver's kick. If you want single-step unlocking, look for the blue/black in the passenger's kick, although I've never had to.