No, they create the law only. They do not have any power to alter rules of procedure. That's exclusively a court power. The only way to change that is by Constitutional amendment. An act of Congress is not enough. Changes to rules of procedure can only be done by Constitutional amendment.
What's this then?
28 U.S.C. 1870.It's a law altering the Federal Rules of Civil Procedure. Chapter VI, Rule 47(b).In civil cases, each party shall be entitled to three peremptory challenges. Several defendants or several plaintiffs may be considered as a single party for the purposes of making challenges, or the court may allow additional peremptory challenges and permit them to be exercised separately or jointly.
http://www.law.cornell.edu/rules/frcp/Rule47.htmRule 47. Selection of Jurors
(a) Examination of Jurors
The court may permit the parties or their attorneys to conduct the examination of prospective jurors or may itself conduct the examination. In the latter event, the court shall permit the parties or their attorneys to supplement the examination by such further inquiry as it deems proper or shall itself submit to the prospective jurors such additional questions of the parties or their attorneys as it deems proper.(b) Peremptory Challenges.
The court shall allow the number of peremptory challenges provided by 28 U.S.C. 1870.(c) Excuse.
The court may for good cause excuse a juror from service during trial or deliberation.