This is a recording of me calibrating a USB2VEC board. Ideally I would have used three cameras to record the procedure - one for the screen, one for the board adjustments, and one to watch the joystick. I only had two cameras, so you can't see me moving the joystick, but when you watch the video of the screen, any large movements of the cursor will be caused by the joystick, not by adjusting the potentiometers. So there are two videos here, and if I knew more about video editing I'ld sync them and join them up side by side, but since I don't, you'll have to start these videos and pause one for a few seconds until they're roughly in sync yourself. Mute the right-hand-side display - the audio is better on the left one. There will probably be some lag from my hosting service so the videos may play through better the second time you watch them. If not try pressing reload. Or maybe better - right-click and 'save video as'.
Because Linux scales the data from all USB devices to be in the same range, this should be a one-time calibration that will work with all joysticks. And it's really only the testers (or people assembling their own boards) who will need to do this - any pre-made boards from David or myself should already be calibrated.
The Vectrex joystick test app is at AnaJoyTest.bin. Setting up the Pi is documented elsewhere.
There's also a close-up of the board which may help while following the video.