The Chief Commissioner may frame rules for regulating the procedure of revenue courts and may, in doing so, extend or apply any provisions of the Code of Civil Procedure, 1908 (V of 1908), with or without modification:
     Provided that until such rules are framed and, subject to them when framed, the provisions of the Code of Civil Procedure, 1908 (Act 5 of 1908), shall, except when they are inconsistent with anything in this Act, or relate to special suits or proceedings outside the scope of this Act, apply, in so far as they are applicable, to proceedings under this Act.