After a decade-long break from the New York stage, Tune returns in a song-and-tap program that's definitely dapper, sometimes schmaltzy, even corny. But as he says (quoting Irving Berlin), ''There's an element of truth in any idea that lasts long enough to be called corny.'' The 6-foot-6 Tune takes vibrant charge the second he struts on stage in white tux and beaded shoes. At 63, his hair is frostier, and his vibrato is occasionally Liza-wide. Yet dancing remains his irresistible gift. All he has to do is pivot and the audience snaps to rapt attention. Tune doesn't spread around much of the directorial magic he brought to breakthrough musicals like Nine and Grand Hotel. Still, through sheer performance alone, he -- and the Manhattan Rhythm Kings -- transform the Little Shubert Theatre into the swankiest supper club imaginable.