I'm not sure but I think there are machines at the airport with internet access - such as the ones at Chamartin station. They work with coins.
Anyway, you don't have to go to the aiport to get the tickets. You can get them also from Iberia offices at Santa Cruz de Marcenado, 2 or Velazquez, 130.
Also, I guess you can buy them from the US and then collect them in Spain (WITHIN 72 HOURS!!!). I don't think they will check your IP address to see if you bought the tickets from abroad.
The best tips from your favourite hostal in Madrid.
Hostal Chelo at http://www.chelo.com
[This message has been edited by Antonio (edited 09-03-2000).]