Head to the pool locker room where you will find a wide selection of guys from students and teachers to University staff and visitors. It's a cruisy place where you can find people engaging if you make eye contact. Guys mostly meet up here and then go to the parking garage next door or elsewhere. The locker room is accessible both from the Pool and from the main part of the Clark Athletic Center. A door just outside leads right to the parking garage.
By public transport, take the MBTA Red Line to JFK station, then pick up the free shuttle to the university. Or driving, take I-93 to Columbia Road, Morrissey Boulevard to University Drive.