For Toyota Prius G3 (Generation 3) hybrid vehicles, you have a few ways to add a smart key to your car. None can be done by chicken dance, you need a programming tool.
1) Buy a virginized (sometimes called “reset”) smartkey on Ebay simply register (add) it with Techstream or other high-end automotive scan tools. No seed code is required.
2) Reset your used smar tkey then do step #1. Most auto locksmiths can reset Toyota G3 fobs with Xhorse Key Tool Max or similar.
3) Reset the smart key ECU on the car using seed/passcode approach and Techstream. Then re-register all your fobs, even if they are not virginized. Just make sure you REGISTER your fobs within 10 presses of the cars START button after car is reset. If not, there’s a chance you’ll brick the car.
BTW, PINS can also also be used to generate Techstream activation codes so you can activate the latest Techstream version on your laptop without buying a license from Toyota.
4) Just pay an auto locksmith to do it. We charge $75 to cut and program a customer supplied fob. We often use our Autel IM608 immobilizer tool and Xhorse Condor key cutting machine. These tools cost thousands of dollars so if an auto locksmith will do it for $75 it’s a fair price to have it done in 20-30 minutes. If you have a working Techstream setup then option 3 is probably the best route to take, but getting Techstream installed and working properly takes a newbie a few hours of research and futzing around.