You need to be hooking the function that calls the enqueue, personally I actually like to register scripts and enqueue them separately, rather than just enqueueing them, as it allows the flexibilty to enqueue conditionally and can save keystrokes down the line at little to no performance penalty. The code you are going to need should look something like this:
add_action( 'wp_enqueue_scripts', 'my_script_holder' );
function my_script_holder() {
wp_register_script( 'svejo_script', 'http://svejo.net/javascripts/svejo-button.js', array() ); //put any dependencies (including jQuery) into the array
wp_enqueue_script( 'svejo_script' );
}
I have not tested that code specifically, but I have used it in almost every site I’ve done. The only caveat I’d give you is that (and this is a bit outside of the scope of your question, but I think it’s good to know) if you’re planning on conditionally enququeing, you may want to hook init to register the scripts to make sure that an enqueue is not called for an unregistered script, as that can cause errors.