Sorry to step on everyones toes here, but I install remote starters and car alarms for a living.

For gods sake, do not get your 12v source anywhere other than the main ignition harness. I forget the wirecolor off the top of my head, It should be easy enough to hit. Just drop the dash pannel and its right off the switch. Probably around a 10ga or 8ga wire. Run a fuse inline and nothing larger than 10A. Anything bigger and I'd use a relay and get the source directly from the battery.

Using the clock or radio circut can overload them very quickly (most toyotas share the radio and cig lighter fuse) I can't tell you how many DIY jobs I've had to fix in my shop because someone went and wired his foglights or something up to his cig lighter and wonders why his radio doesn't work anymore.

Again, sorry if I stepped on anyones toes