Ordering Posts

I’ve got a theme that I’m using and it’s throwing posts up on a slider on my home page but I would like to order the way they show up. The code currently in place is:

<?php
//OptionTree Stuff
if ( function_exists( 'get_option_tree') ) {
	$theme_options = get_option('option_tree');
	$homeCategory = get_option_tree('home_category',$theme_options);
	$homeNumber = get_option_tree('home_number',$theme_options);
}
?>

	<?php
	$temp = $wp_query;
	$wp_query= null;
	$wp_query = new WP_Query();
	$wp_query->query('cat='. $homeCategory .'&showposts='. $homeNumber .''.'&paged='.$paged);
	while ($wp_query->have_posts()) : $wp_query->the_post();
	?>

And the way I would like this to be ordered would be the following:

orderby=meta_value&meta_key=event_date&order=ASC

I’ve never used option tree before in obtaining information from some theme options, so I’m kind of confused on how I would integrate that ordering method with the other code. Any help is much appreciated, thanks!

Jarth