Anything is possible, but keep in mind you'll be competing with people (individuals as well as companies) who will happily bid very low (even down to $5/hr or so, possibly less). You will also be wrestling with clients who see pages and pages of projects (with accepted bids) along the lines of "Build me a Facebook clone, I have a budget of $250" and think its normal. So not only do you have all the marketing issues of a freelancer, with all the time sinks that go with it, you are targeting an audience of clients who are unlikely to pay well.

In other words, these sites are sites where a specific commodity--dirt cheap developer labor--is bought and sold. You'll almost certainly do better in the commodity market of well-paid, but not as plentiful, developers in your home country.