I didn’t know you could access it from the resort itself, but I do know that we on the tour were permitted to walk through the official entrance, a 20-something ton steel door carved into a large rock!
See their website!
The vast majority of the dorm rooms have been long converted to data storage for a railroad company.
What the resort has preserved is the decontamination area, the kitchen and cafeteria, the auditorium with the Presidential Seal podium for briefings, the infirmary, a few dorm rooms, and a couple other items of interest; the rest of the massive bunker has been converted.
It really is a gigantic resort. I guess it’s not as profitable as it used to be, because since I was there in 2009 they’ve added a casino (albeit a tasteful one)!