The primary successor for HiTechnic products maintains a Downloads Page with various EV3 programming blocks. BuilderDude35 Downloads:

environment is essential for competitive robotics, especially in WRO soccer events. Because HiTechnic was acquired by Modern Robotics, many official download links have moved or become difficult to find. Downloading the HiTechnic IRSeeker EV3

To program the sensor, you must download the custom .ev3b block file. While the original HiTechnic site is no longer active, you can find the necessary files through several reliable mirrors:

Once you have downloaded the .zip or .ev3b file, follow these steps to import it into the LEGO MINDSTORMS EV3 Downloads - TESSLAB ROBOTICS

A well-known community resource, BuilderDude35, hosts "lost" HiTechnic blocks, including the IR Seeker V2 , to ensure continued access for builders. Provides direct links for the HiTechnic IR Seeker among other third-party EV3-G blocks. How to Install the Block in EV3-G