Practice by attorneys for the United States is governed by LR83.2(a). 

An attorney who is in good standing as a member of the bar in every jurisdiction in which admitted to practice, and who is not subject to pending disciplinary proceedings as a member of the bar in any jurisdiction, may appear and practice in this court as an attorney for the United States, or for any agency of the United States, or for an officer of the United States in an official capacity.  The court may at any time revoke such permission for good cause without a hearing and any attorney appearing pursuant to this rule is subject to the disciplinary rules and jurisdiction of this court.

For electronic filing access register via PACER at pacer.uscourts.gov. Detailed instructions are located here.