I was there in November with my nephew, and we basically walked right in. Although, we did catch some athletes on the way out, they basically held the door open for us. I think otherwise the door might have been locked. We took a couple of pictures at the edge of the court and left.
So, the short answer: the door will likely be locked, but it is worth walking over and trying it out, especially in the off season. If it isn't open, there is still a "hall of champions" area in the building next to Cameron with displays of trophies and nets and that sort of thing.
Hope you have a great visit.