The only overt evidence for this was that in the early '90s he wore one of those pink triangle "SILENCE = DEATH" t-shirts in a couple of photo shoots and interviews.
He also made a few comments in interviews about AIDS awareness and IIRC even once mentioned that he hadn't really fit in with his basketball teammates in college and that they'd called him a fag in the locker room.
A few weeks ago I was listening to NPR's "Wait Wait Don't Tell Me" and he was the celebrity guest in the "Not My Job" segment.

“Standing on the podium watching the flag being raised was one of the most incredible experiences of my life,” she said from her home in Cleveland.
Moceanu thinks the next person to hear the national anthem could be World Champion Evan Lysacek, who is in second place heading into Thursday’s free skate at the 2010 Olympic Winter Games.
“As an athlete, I think the more support that you get, the better you feel about yourself,” said Moceanu, who has long retired but still participates in gymnastics clinics.
“I choose to come out and let everyone know I support Evan because I want him to know that I’m behind him, I’m supporting him.
well, then, you might be Tony Kornheiser (just suspended from ESPN for dissing Hannah Storm). The importance of being Snooki: Jersey Shore kids seek to trademark their names. C.'s "newsbabes" are all great friends, it turns out.
Senate staffer fired for writing an indiscreet book.
taken-by=alyraisman Before joining the show as a competitor, Raisman and her Olympic teammates made a guest appearance on the “Dancing with the Stars: All-Stars” finale.
Dancing in the freestyle routine of fellow Olympian Shawn Johnson and partner Derek Hough, the Fierce Five added a few extra flips to the competition.
Given what little else I knew about Ament personally -- lapsed Catholic, athletic but artistic, studied graphic design in college, penchant for flamboyant hats, came from a small town in Montana but said he'd known from the time he was 12 or 13 that he had to get out and be in a bigger city -- well, I connected the dots in a certain way.