I just checked the code.
Once you have emma.storyLvl >= 60 (somewhere along the sacred sex quest but not finished yet) you have the option, while talking with Olivia in the school hall, to go into the maintenance room (and thus have sex with Abigail/Naomi and unlock the VIP room sex scene) if you have the key (it's in the principal's office) and anna.storyLvl >= 20 and less than 80 (if you were introduced to the aliens, you've gone too far).
I was quoting from memory, mostly. But it seems that you can't advance too much on either quest. If you advanced too much and can't trigger this and don't have a save file from previously, you can use the console to change anna.storyLvl to 70 so you can finish this, then trigger the quest again, or change the value back to 80.