notwithstanding
section 3104 of title 5 or the provisions of any other law relating to the appointment, number, classification, or compensation of employees, make appointments of scientific, engineering, and professional personnel, and fix the basic pay of such personnel at a rate to be determined by the Secretary at rates not in excess of the highest total annual compensation payable at the rate determined under
section 104 of title 3, except that the Secretary shall appoint not more than 25 personnel under this paragraph;