This topic discussion pointed me in what seems like the right direction. I was able to book a COPA/Co combination from Buenos Aires to Burlington, VT, with plane and airline changes in Panama City and again at EWR. One downside is that the timing of the once-a-day flights means that one has to overnight in Panama City each way. The person taking this routing to come here is from Argentina, and he does not need a visa for Panama (those of us from the US need visas) so the overnight won't be a problem. The lowest fare I could get was around $900 and that only got him as far as JFK. Maybe there are better angles, but 35K is remarkably few miles considering the distance involved.