Reiterating what TtT said, "Get a new one." There isn't a resettable feature on the ECU, it doesn't have DIP-packaged ICs seated on sockets that you can take out and reset them. These are all surface-mounted ICs which are probably hermetically sealed. Plus, where are you going to get a Toyota proprietary schematic of the ECU?
In fact there are a few companies specialised in testing / repairing ecu's (there about 2 or 3 in the United Kingdom, perhaps in the US ?)
Instead of buying a new one, Id' go for a used one, I don't even want to think of how much it would cost.
As for installing it, you can really easily do it yourself. It is located behind the glove box, you'll have to unplug it and plug the new one in, and that's it !
BTW are you really sure the problem is with the ecu ?
It sounds more like an alarm problem. Having the rear lights out has nothing to do with the ECU, let alone any lights. Better check out the alarm. Sometimes if the alarm is draining the battery supply, it's possible that these electrical mishaps can occur also.