Change Database Prefix While in Loop

I have 2 wordpress websites running off the same database, but each with a different prefix. I need to be able to query from site1.com while using site2.com

Something like this:

<?php get_header(); ?>

//Switch to 'pre1_'

// The Query
query_posts( $args );

// The Loop
while ( have_posts() ) : the_post();
	echo '<li>';
	the_title();
	echo '</li>';
endwhile;

// Reset Query
wp_reset_query();

//Switch back to 'pre_2'

<?php get_sidebar(); ?>
<?php get_footer(); ?>