Change get_posts to loop.php suitable version

I did't know that get_posts don't work with loop.php. I already have this great loop.php file and I want to use it. I created this code:

$pageposts = get_posts(
    array(
        'relation' => 'AND',
        'post__in' => $postid,
        'post_type'   => 'event',
        'post_status' => 'publish',
        'meta_query'  => array(
            array(
                'key'    => 'st_date', 
                'value'  => array($todate_s, $frmdate_s),
                'compare'=> 'BETWEEN',
                'type'   => 'DATE'
              ),
        ),
    )
);
if ( have_posts() ) : ?>
<?php get_template_part('loop'); ?>
<?php else : ?>//etc

How I can convert the get_posts(//etc) to something that work with have_posts() and get_template_part('loop') at the end of my code? Is this possible?