What Happened To Everyone Who Used Cerebro?
3. Scott Summers
Typically, a guy like Scott Summers, otherwise known as the mutant Cyclops, wouldn't be able to use Cerebro under any circumstances. He has no telepathic abilities whatsoever and has no training in their use. All of his skills are related to his leadership abilities and the powerful beams he can fire from his eyes.
Of course, Marvel Comics' X-Men titles haven't always been the same as they are now and even devices like Cerebro have gone through some rather significant changes. While most people know of it as a large room with a central core holding a telepathic helmet, it didn't start out that way.
Back when the comics first started, and Cerebro was introduced, it was little more than a powerful computer, which fed information to Professor X's desk. It also used punchcards, but seeing as this was the early 1960s, that actually makes a lot of sense.
Scott used the computer in issue #7, which was also the first appearance of Cerebro. He used it to track down the evil Mutants running about causing all sorts of problems, but he also managed to use it to try and track down other evil Mutants who might eventually become a problem for him and his team. This was about the only time Scott used the device as it was later upgraded into the telepathic interface we know today.