A cueva will do transfers and give you dollars. You have to have a contact to do it (which can be found) because they operate in the gray area of the law. Casas de Cambio indeed will have to go through the hoops Steve talks about because they are official and transfer the money through the central bank, while cuevas work through public bond trading and such and local dollar/peso exchanges which are off the books. You transfer the money to a bank account outside of Argentina (as r2d2 mentioned) and they will give you dollars or pesos (your choice) here. When they give you pesos, they will give you a good rate because you've already paid their transfer fee.
Notice I'm not talking about arbolitos, or the unofficial change houses like what you find on Florida street or other places - arbolitos are like the public branch of cuevas (that's where they get their cash from, if you've ever been in an arbolito and seen a guy with backpack come in and talk with the guy changing money - he's brought fresh pesos from a cueva) and you can't really get introduced to a cueva that will handle transfers like this through them, unless you've been going to one for a while and make "friends" with them and they trust you enough to go to the bosses to find out what can be done. Some arbolitos don't even have enough pull to ever make that kind of a contact with the guys upstairs, or maybe they're independents who don't have cueva contacts.
A problem with cuevas used to be that Cristina was making life very difficult for them and they were charging 6% or more of the transfer amount because of the risk and difficulties involved. I haven't used a cueva for money transfer for two or more years (once they hit 4% it was way too much for me) so I don't know what the current condition is, but I would expect these "informal" transfers to go back down to 1% - 2% before too long, if they haven't started coming down already.
Also, to the OP - you can find people here who have dollars and bank accounts outside of the country and would be willing to make the trade. May take a while to find people to do this, but maybe a little bit here with a private individual, some with Xoom, maybe a trip or two to Uruguay to get dollars out of the ATMs, maybe even someone bringing cash for you from the States, etc.
Welcome to Argentina, where not very many things like this are easy to accomplish
