After the roommate's SO tells you about the glory hole and you've completed the challenge, you may return to the porn shop and use it, provided your disinhibition is above 4, if I'm not mistaken. I don't think there is any other way to unlock this currently, which is a bit of a let down. I can imagine a scenario where the properly disinhibited MC can turn any restrooms (School, Dorms, Shopping Mall, River Rat, Quickie Burger, etc.) into gloryholes, and they wouldn't need to find out about it from the corruptive NPC. And since the game features pee play already, those truly depraved watersport enthusiasts could offer their services as human urinals.
The very idea of the corruptive roommate's boyfriend/girlfriend is a bit of a hit and miss in my opinion. The challenges would make much more sense if that person was, at least initially, the only source of sexual depravation for the MC. But the MC may become a total slut/perv just fine without their 'help': watching college cams, masturbating (this is stupid, really, I've yet to meet anyone in real life who's become a shameless slut through chronic masturbation), dressing lightly, streaking, peeping, flirting, partying, etc. For a relatively sexually experienced MC, some of those challenges are not challenges at all. The 'wear a skirt and no panties to the class' challenge comes, more often than not, quite late in my playthroughs, usually when this is the way my Exh 3+ MC have been dressing on a daily basis for quite some time.