Xoom claims it will allow pickup of US dollars, from BBVA Banco Franco, for an extra fee, using this language:
Cash Pickup in U.S. Dollars
Service Fee: $26.50
BBVA Banco Frances - U.S. Dollars
BBVA Banco Frances branches are open Monday - Friday from 8:00am - 1:00pm or 10:00am - 3:00pm...