This can be done in the biomedical section, inside the medical area. You will need to find the skull, if you have done the skeletina achievement, it should be on the skeleton in the exam facilities, otherwise it will be inside the medical storage locker. The key can be found in the desk drawer in the medical office. Take the skull up the elevator to the hub area and put it through the micro-g basketball hoop. If you have completed the game, you can reload your game and backtrack from the end to any part of the Tacoma.
Here is a video guide with English commentary!
Here is a playlist of guides for this game!
https://www.youtube.com/playlist?list=PL-HeW6XkKdUI9Dx_EewXg...