You want to race Ruta 40? I think it's kinda late. You still can pay for the rally but it starts in 40 days. I don't know how long it takes to bring the bike from the US to Argentina.
Here's a bit of information, very usefull BTW
registration: $ 18.500 (3572 dollars). It includes you + 1 assistance guy (you have to pay 489 dollars for each extra guy), all the meals, insurance, iritrack, gps and sentinel. You have to pay for the fuel,fees, hotel, towing, gps iritrack and sentinel bracket, and the registration of the assistance vehicle.
You do an advance payment of 869 dollars (before 6/5/2013), and you pay the rest when they check your bike.
That's all I know, maybe you can email the organisation : email@example.com