Elizabeth Eulberg has quite the day job. Her very intimidating title is Director of Global Publicity for Stephenie Meyer, which means she manages planet Earth’s insatiable demand for theTwilight mega-author. But on the weekends the 35-year-old Wisconsin native turns off the ringer to her vampire phone, holes up in her Hoboken, apartment, and writes 5,000 words a day. (She awards herself a cupcak…