Almost 50 years later, Betty Boop is back with her breathless, squeaky voice, big eyes, spit curls, macromini-skirt and perky "chin-up" optimism. She stars in a half-hour animated, musical special, The Romance of Betty Boop, at 7:30 p.m. Wednesday on CBS-Ch. 2. Inspired by the original "It" girl, Clara Bow, Boop made her debut in 1930. By 1939 her career ended. Several women played her voice during those nine years. In this show the voice belongs to Desirée Goyette, a composer who has written music for "Charlie Brown" specials.The year is 1939, and Boop lives in a one-room walk-up apartment in New York. By day she works as a shoe clerk and by night as a nightclub tap dancer. Musical numbers of the era include "I Want to Be Loved by You" and "I Only Have Eyes for You". There's talk of more if the show's a rating success.