The official story is that the kid was on his (cancer) deathbed in the hospital and is told that he will die. Some staff at the hospital or a family member asks him if there's anything they can do for him and anyone he wants to meet. The kid points to a TV with MJ on (a concert or a music video) and says he wants to meet MJ and the staff says that they can make that happen.

One meeting with MJ leads to another and the kid gets to be a regular guest at Neverland or even stays there as he's going through chemotherapy.

The segment from Bashir's doc seems to be some time after the cancer is gone or it has gone into remission at that point.

I think this is basically the story.