I live in Argentina, and I've always wondered if (given the case of having something worthy) I'd be able to submit it to publishers in, for example, the USA. Of course the writing would be in English.
Is it possible? How can it be done?
It's absolutely possible. If you already have a good idea of the publishers you would like to work with, check their web sites for submission information. If not, try subscribing to something like Writer's Market to get the info.
Do be aware that some publishing houses shy away from publishing international authors because they aren't sure how to parse the legal issues. We don't exactly get a ton of Argentinian authors around here, so they have to be willing to invest in the legal expenses for covering all their bases. However, some publishers are quite used to these sorts of things, and won't take it into account much when evaluating your manuscript.
You also might look at Argentinian publishers that are affiliated with or have distribution agreements with American companies. I don't have direct experience in this area, but I've seen it bring things into the US pretty smoothly, and I'd imagine that since we have such a huge market, it's not an uncommon thing for foreign publishers to be prepared for.
Getting an agent and/or getting published in your own country may be easier than trying to sell your work overseas by yourself.
I don't know the details of how literary agents operate in countries outside the US, but I believe it is fairly common for US literary agencies to have "partner" agencies in other countries. Then, if a book does well in the US market, the partner agencies can pitch it to publishers in their respective countries.