What Happened To Everyone Who Used Cerebro?
1. Kitty Pryde
Throughout the publication of the X-Men titles, there have been occasions where Professor X wasn't around. He has been captured, killed, and had his mind in other people's bodies, which meant he wasn't always there to operate Cerebro.
During one of these instances when Xavier was with the Shi'ar, Kitty Pryde was left to use the device, but without any telepathic powers of her own, a unique upgrade was required.
She got to work on altering the system so that it could be used by people without any telepathic skills or powers. When she was finished, she was able to use it... and use it well considering she had no powers of her own outside of her phasing ability.
The main reason she needed to use Cerebro at the time was to find Nightcrawler. He had previously disappeared following a rather nasty battle with the Sentinel Nimrod, and the team had no way of tracking him. Once Kitty was able to strap a modified Cerebro onto her head, she was able to successfully track Nightcrawler wherever he was on the planet, which proved you didn't have to be Charles Xavier to telepathically find Mutants.