You would probably have to pay a ridiculous setup fee, like 10% or something, but depending on how much you're donating, that could be the easiest way to do it (and it'd probably be the method I'll use when I turn 18, to avoid having to set up anything complicated like my own credit card or bank account transfers). But you will at least need to have a PayPal account, so if you could get parents, friends, or someone who is over 18 to help you out with that then you'd be in perfect shape.