Yeah, if that wallet thing is programmed as a master key, and I would assume it is, then you're okay. In any event, to program a new key to the immobilizer, you'll need something in your possession registered as a master key. It wouldn't be a bad idea to also purchase a normal key without the fob part attached and have that programmed as a master that you can put aside for emergencies.
I looked up all of the info on it, and it appears that it is pre-Techstream. It says there are two ways to register a new master key. One is with the brake and accelerator pedal, the other is with the hand-held tester. This hand-held tester is what they used before Techstream was introduced. It's the old Toyota factory scan tool.
I have the procedures for the 2002 RX300 wireless transponder registration, key registration, and immobilizer reset all printed out here. And yes, it gets expensive to do it without a master key because the dealer will charge you for the immobilizer reset which is done using their scan tool along with a pass-code obtained from Toyota Information System. It says some early ECM based immobilizers cannot be reset using Techstream and to refer to some other information charts on doing it...which I didn't bother with because you won't be messing with immobilizer reset on your own.
In the end, you probably have access to all of the instructions you need to program it, and if you don't, I'll post up exactly what you need for your car printed off from TIS. Hopefully that card is registered as a master key. If it isn't, I don't think there's any way around taking it to the dealer and having them do a reset on your immobilizer system. Good luck and let me know if you need any of this info.