The only time in recent memory that FranceBillet or TicketNet have refused to sell tickets overseas was for the match against Germany 3 or 4 years ago due to hooligan concerns. Don't think the same worries applies too us. I got a pair of tickets for the match in 2004 through FranceBillet no problems.
Also, there was over 30,000 Irish supporters in the Stade de France that night. Not just in the Sud Tribune, but dotted all over the rest of the ground, and it still wasn't a sell out. In fact France matches rarely are. I've been to several French internationals at the Stade de France and the only time it was a full house was when the played Italy in the Euro 2008 qualifiers. But that was 3 months after they met in the World Cup Final.
As mentioned by ptegan above, you can always buy tickets through FNAC, then collect them when you arrive in Paris.
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