It took some time to get it accomplished, but women in Congress can now use the House gym. The longtime exclusively male inner sanctum kept women from working out there, but a move led by Rep. Barbara Boxer succeeded in changing that. It took Boxer and Reps. Marci Kaptur and Mary Rose Oakar, singing a parody of "Five-Foot-Two, Eyes of Blue," to do it, and now there are separate changing rooms and even plans for aerobics classes. The sacred hiding place away from constituents and staff will never be the same again . . .

Figure skating star Dorothy Hamill, who is ice skating this week, in this heat, on an outdoor rink on Wolf Trap's Filene Center stage in "Festival on Ice," says she is negotiating with the Disney corporation for the rights to use the musical score from the hit movie "Mary Poppins" for a theatrical "ice musical" based on the children's story . . .

M, the slick, expensive magazine that boldly describes itself as being for "the civilized man," has made up a new list of "Men Who Look Great." Among the 61 named are President Reagan, Virginia Gov. Charles Robb, Newsweek managing editor Kenneth Auchincloss, Jordan's King Hussein, Sen. John Heinz III, former senator Abraham Ribicoff, Washington real estate agent Dale Denton, John F. Kennedy Jr., political consultant Roger Stone and actors Harrison Ford, Warren Beatty and Robert Stack . . .

Sen. John C. Stennis, the nation's senior U.S. senator, plans to celebrate his 84th birthday Aug. 3 back home in DeKalb, Miss. About 5,000 are expected for the celebration, including a few out-of-towners like Sens. Strom Thurmond, Barry Goldwater, Sam Nunn, Lawton Chiles and Joseph Biden . . .