Two bestselling authors, avid fans of the Boston Red Sox eager to see them take the World Series this year, are combining to write a book for Scribner that they hope will climax with the elusive victory. They are Stewart O'Nan and Stephen King, and the idea for the book grew out of e-mails they exchanged about their favorite team. In the book, which publisher Susan Moldow (also a fan) acquired from O'Nan's agent, David Gernert, each author will contribute diary entries as they follow the Sox through their spring training, attend some games, together and separately, and review the Sox's season, whatever the outcome. The book, which was bought for North American rights and audio, will be edited by Nan Graham and will appear as soon as possible after the Series.