Since I recently had to tackle this for a friend whose key was not turning in the cylinder, I decided to take some pics of the process to make it easier for the next guy...
Remove the black bolt above the dead pedal to remove the cover next to driver's left foot. This must be removed to get at other screws that need to be removed.
To remove the plastic knee panel below the steering wheel, you will need to remove the hood latch mechanism that is mounted to it. Start by removing the two screws shown:
Pull the hood latch mechanism out so that you can get to the cable:
Remove the cable by rotating the cable in the handle so that the cylinder at the end of the cable can be rotated and the cable slid sideways through the handle:
Remove the screw on the lower right corner of the knee panel:
Once you have the lower knee panel off, you must also remove the metal bracket behind it that holds the OBD-II connector. There are 5 screws holding this panel in place (not shown), all fairly easy to find. Here is the OBD-II connector mounted to the metal panel. It can be removed from the panel by pressing the clips on the sides:
Now you can remove the cover around the ignition switch by pulling it away from the dash and popping the two clips out of the dash.
Remove the light ring from around the key cylinder by removing one screw at the bottom:
The screw can be better seen in this pic with the light ring removed:
Now you can remove the key cylinder by pressing a small shaft into the hole at the bottom of the key cylinder. The key must be in the ACC position:
If you can't get the key to turn to ACC position, you may have to get access to the back of the cylinder to turn the key shaft. By crawling upside-down under the dash, you will see the plastic switch assembly screwed to the back of the key cylinder:
By removing two screws and unclipping a few of the attached connectors, you will be able to remove the switch and see the end of the key shaft:
A pair of needle-nose pliers can then be used to gently assist turning the key to the ACC position, and press the release button on the bottom of the cylinder as shown in the photo above.
Here's a pic of the key cylinder being removed from the housing:
...and a view down the empty housing:
Once I had the key cylinder out, the next decision was to replace or repair. Replacing with a new cylinder was complicated by the fact that this Camry came with a chipped key. Changing the cylinder meant getting a new chipped key and spending another $80 at the Toyota dealer to get it programmed to the VIN. Getting a non-chipped cylinder would work, but the owner would have to keep the chipped key and press it against the non-chipped key while starting the car to satisfy the transponder.
What we came up with (at the suggestion of the Toyota parts guy, no less) was to take the cylinder to a locksmith, where he rebuilt the cylinder with new tumblers, for about $30. Problem solved!
Put it all back together in about 30 mins, good as new!