Jailbreak: Connecting to another AppStore

[nightmage]

Hi,

I have a jailbroken iPhone and there's no AppStore for my country (Uruguay). I couldn't create an AppStore account for the U.S. because they ask you to have a billing address in the U.S. but I could create an account for the Argentinian AppStore. The problem I'm having is that when I try to install some app from the AppStore I'm told that my account is only valid for the Argentine AppStore. How can I connect to that AppStore from my iPhone? Can I do it? What file do I have to edit?

Thanks.