BE LIKE KATE: Ever wonder what it takes to be an Oscar-winning actress? That is, in addition to talent and a good agent? According to People/Yankelovich POP Monitor Profiles, which measures the star power of 1,000 celebrities, char acter and likability seem to count for a lot. And when it to comes to performance and personality, the Academy Award-winning actress against whom all others must be measured is four-time Oscar winner Kath-arine Hepburn. That may be humbling news for this year's Best Actress nominees, particularly when they look at the scores of the past three winners. Susan Sarandon, Jessica Lange and Holly Hunter are all at or above average in terms of being hot, believable and trustworthy, and none are yet overexposed. But their scores don't yet approach those of Ms. Hepburn. And when it comes to uniqueness, Ms. Hepburn is the reining queen, with the highest one-of-a-kind score of any female celebri ty monitored.