I got the impression it was a paperwork exercise to get the lincece much like the CAA-FAA conversion, but I think it worked from FAA-ArgentinianAA. Never did it though, so I'm not 100% sure. Its not a bad idea to at least learn local procedures before holiganising someone elses airspace though, and it wouldn't hurt to know their laws. Not too difficult if you know their language, but far beyond my "dos cervesas" standard of spanish.
Amoung the memorable trips was Buenos Aires to Colonia in Uraguay (just across the river). It was probably not much more expensive than the tourist ferry across the rio plata, but much more slylish. EVERYONE was onthe take though, from the half dozin Argentinian officials who had to sign paperwork to let you out to the taxi fares of the Uraguayan officials, who had to come and stamp our passports (in and out at the same time) when we got there. I think we paid $100 or £100 in fees over the flying costs. Still a worthly trip though.
The best place I flew from was called Hangar Norte on an airfield in a northern BA suburban. A quick google revealed that they don't seem to internet anymore, but I'll make further enquiries...