An Argentinian (pilot) friend of mine who lives in Europe has looked into this, as we are planning to do this at some point. From what he told me - mind you, this is not official - the answer is 'doable, but not easy'.
There appear to be two obstacles to anyone w/o an Argentinian license flying there:
- the conversion process which, according to who you believe, requires an air-law exam in Spanish
- the non-availability of rental a/c
In reality, the latter is probably the bigger issue. GA seems to revolve around private owners and/or clubs there, with no provision for non-owner / club member flying.
The easiest in your case would probably be to find a local pilot, offer to pay for the fuel and go flying with him. By far the easiest (and cheapest) route to a bit of flightseeing.
Enjoy!