Jake,
Check out this site for the type of connector and voltage used in Argentina (and everywhere else for that matter).
http://kropla.com/electric2.htm
It is the "Australian" type that he needs.
If he hasn't already bought Apple's adapter kit I'd recommend he just buy a travel adapter in Argentina, or in the Airport departure lounge on the way out - they only cost a couple of bucks and will work just fine. When I moved from Canada to the UK nearly two years ago I thought the Apple kit was overpriced - spent £2 on the relevant travel adapter that I'm still using.
Good luck,
Gareth