Following instructions were taken from YouTube instructions. It worked for my 2005 Seinna very nicely.

Problem: What to do if you need an extra spare key for your van? Most vehicles now have a smart anti-thief key that you can't just go to a local hardware stores to duplicate. They all contain a small transponder that validates with ECU, else engine will crank but not start. My $3 dup key from home depot did just that. There are after market chip key that you can program thru elaborate sequences of break/door combinations, but I'm too lazy & cheap.

Supplies

Your original chip key + spare. Incase you ruin this one.

Duplicate key from any locak lock smith. Make sure it does unlock the car & turns to accessory position

Utility knife, flat head screw driver, super glue, masking tape, clamps

Step 1: Surgery Time

As seen on YouTube, most Toyota chip keys have a softish plastic head. Clamp it down and scribe a cutting line, then progressive make deeper cuts until you hit a harder surface. Use screw driver & whatever means to separate the inner key. The transponder is a very small, black ceramic thing. Use care & separate that too.

Step 2: Locate the Magic Sweet Spot

For the auto geeks, chip keys in modern cars authunticate by an antenna ring on the iginition housing. Once the chip is remove, you need to place a non-chip key and locate the spot where car can start.

Try starting the car while holding chip with the other finger. Reposition it untill you have located the magic spot. Mine was around 9 o clock position.

DON'T LOOSE THE CHIP !!

Once working, tape it temporary and test with all other keys for this car. Apparently, you can start with a chip key on top of this hack also. Make sure all starts before moving to next step.

Step 3: Glue Down Everything

Put a small dab of super glue on the transponder chip, tape it down and don't touch. Put the un-chip inner key back to plastic housing. Take some super glue and clamp down all the cut seams. Clamp down real tight & let dry overnight.