How to configure HTC Desire for 3g connectivity in Peru?

How can I configure an unlocked HTC Desire for 3g connectivity in Peru? I have managed to add an APN so that I have EDGE but I would like to use Claro's 3.5g. I also have an iPhone with the same kind of dataplan that has 3g pre-configured so I am hoping that it is possible. I realize that this is a very specific question but I can´t get any worse help than at the Claro office...