//functions.php:

<?php
function setup_filter_rewrites()
{
    add_rewrite_rule('^sok/events/([^/]*)/?', 'index.php?p=1&kategori=$matches[1]', 'top');
}
add_action( 'init', 'setup_filter_rewrites' );

function setup_filter_query_vars( $query_vars )
{
    $query_vars[] = 'kategori';
    return $query_vars;
}
add_filter( 'query_vars', 'setup_filter_query_vars' );


//index.php:

<?php
$my_category = get_query_var('kategori');
echo $my_category;
?>
<pre>
<?php print_r($wp_query); ?>
</pre>

<?php
if ( have_posts() ) :
while ( have_posts() ) : the_post();
?>
<h2><?php the_title(); ?></h2>
<?php
the_content();
endwhile;
endif; ?>