“During fiscal year 2002 and thereafter, the head of an entity named in 3 U.S.C. 112 may, with respect to civilian personnel of any branch of the Federal Government performing duties in such entity, exercise authority comparable to the authority that may by law (including chapter 57 and sections 8344 and 8468 of title 5, United States Code) be exercised with respect to the employees of an Executive agency (as defined in 5 U.S.C. 105) by the head of such Executive agency, and the authority granted by this section shall be in addition to any other authority available in law.”