Wyoming does not provide special admission rules for government attorneys licensed in other jurisdictions.
However, Wyoming provides a Wyoming Multijurisdictional Practice Rule (MJP) within its rules of professional conduct. Comment 7 to that rule provides an interpretation that exempts government attorneys from the unauthorized practice of law.
Please also see the Wyoming Bar Reciprocity page to view the requirements for Admission on Motion and the Wyoming Pro Hac Vice page to view the requirements for admission to a particular proceeding.