A man who said he was fired from his job at a trucking firm after his wages had been attached to pay child support sued his former employer for $5 million in Los Angeles Superior Court. John R. Stevenson said in his civil suit that Watkins Motor Lines in the City of Commerce fired him last September after the firm had made one court-ordered payment of $300 directly to his former wife, Linda. In December, she filed a similar suit against Watkins, seeking $1 million in damages. Her suit said she obtained a court order to attach her former husband's wages after he failed to pay more that $6,900 in child support. Both suits maintained that California law specifically prohibits employers from firing workers whose wages have been attached for child support. Company officials could not be reached for comment.