BOSTON — THE world is wired for MTV.Engulfing the globe, MTV is available in 40 countries and 194 million households as of this month. That will grow to 71 countries when MTV celebrates its 10th birthday by launching MTV Asia in September. Most international MTV programs have a local flavor, says Tom Hunter, vice-president of international programming for MTV in New York. This means mixing local music with international hits, and using hometown "veejays" with the right languages. In Europe, MTV is broadcast in English, but many of the videos are by independent-label British and European singers. In Brazil, as Mr. Hunter tells it, kids in one small town without MTV are so enamored of it that a group of 50 teens wrote out "I WANT MY MTV" across a banner and marched to the mayor's house to protest. Still another fan was so determined to win dinner with Paul and Linda McCartney in London that he drove his car filled with 10,000 postcard entries to the MTV station, because he couldn't afford the postage. (Though he didn't win, Paul McCartney was so amused that he invited the chap to dinner anyway.) Viewers in Latin America get less MTV than some audiences, but more of it is in Spanish and by local performers. "MTV Internacional," the hour-long Spanish-language program, is also available on Telemundo Network in the US. According to Hunter, when Soviet soldiers invaded Vilnius, Lithuania, in January 1991, they began illegally broadcasting MTV Europe from the government TV station. "We've asked them to turn it off," says Hunter. "But when we found out the person in charge was a colonel in the Soviet Army...."