All such attorneys or agents seeking approval of their employment by Indian tribes or desiring to represent individual claimants before the Indian Bureau shall be required to comply fully with the regulations of the Department promulgated September 27, 1917, governing admission to practice, and to take the oath of allegiance and to support the Constitution of the United States, as required by section 3478 of the United States Revised Statutes (31 U.S.C. 204).