I did this today. This is exactly what I did and it could really not have been easier.
Transfer under $5000AR to myself, from my US bank account.
I used my cell phone number from AR for the first attempt and I recieved an email that my transaction was cancelled.
I called
Xoom and the rep tried to call me, it didn't work, so I gave her a land line, told her dial 54 11 xxxx xxxx, answered, and confirmed my transaction. The rep asked me how long I would be in Argentina ("don't know"), how often I planned to transfer money ("not sure, maybe monthly or to my boyfriend") and that was it.
5 minutes later I did another transaction with the new land line phone listed, and got confirmation.
Then I went to the Libertad office of More, gave them the printed confirmation form Xoom and my passport with a photocopy (seemed unneccesary but he kept it so... not sure). I also had my confirmation of domicilio form the police here but he did not ask for it. He asked what my "activity" here was and I told him "tourist". I signed a bunch of papers, and he handed me my money at the rate published on xoom today, in pesos.
The place is not sketchy at all, is clean, I wouldnt walk around downtown with a ton of money, but it's not a kiosco or anything, more like western union.
Hope that helps someone else do the same as me!
Cheers,
Betha