It's been 10 years, but I regularly did that from roughly 2010-2015. The facilities have changed significantly, but really you just walk back there. There used to be a guy in an orange hat who power tripped and kept people from going back there, but it's just free seating, get up close and personal, and don't be an autograph hound. Enter by the area behind the right field of the stadium, walk the path below and sit in the bleachers between the two fields. Once games get going, there's usually two games going at once.