In 1825, he became the second official librarian of the Georgetown University Library, after Thomas C. Levins, who had filled the position since 1824, was dismissed from the Society of Jesus and left for New York City. When Feiner relinquished the office the following year, James Van de Velde succeeded him. When the president of Georgetown College, Stephen Larigaudelle Dubuisson, was permitted to resign the office, and he eagerly set sail for Europe, Feiner was appointed president May 4, 1826, by the Jesuit provincial superior, Francis Dzierozynski. He assumed the office on July 8, 1826, despite suffering from advanced tuberculosis and unable to speak even basic English; indeed, Feiner never mastered the English language. When Feiner learned of the provincial's order, he is said to have entered Dubuisson's room sobbing and declaring that he was neither competent to hold the office nor desired it. While president, he simultaneously ministered to the congregation at Holy Trinity Church in Georgetown. While president, Feiner was also a professor of moral theology in 1828 and of dogmatic theology as well in 1829. Given Feiner's failing health, John W. Beschter left for the college in anticipation of having to succeed Feiner as president. Overall, his administration of the college was deemed lackluster. He resigned the presidency on March 30, 1829, and on June 9 of that year, he died at Georgetown College. There, he was buried in the Jesuit Community Cemetery.