Techstream refers to Toyota's factory diagnostic and reprogramming tool, allowing technicians to access vehicle data, troubleshoot issues, and reprogram ECUs, and is available in both full and "Lite" versions. This quick write-up assumes either you, your installer, or technician has access to Techstream.
When you are removing the OEM, computer calibrated passenger seat, with an upgraded aftermarket seat, you must get the seat's weight to the same as you are taking off. With the Tolerance Stack mounting system the solution is built-in. With addition of washers under a tensioned spring you can calibrate by adding washers to adjust the pressure of the spring.
If its determined that you need to use Techstream to accomplish the zero-point seat calibration, simply follow along with the written instructions found here: https://www.tolerance-stack.com/technical or follow along with this video: