Limit by custom field/meta value

Hi!

We want to limit the plugin to show only posts that have the custom field "rss" set to 1.

To do this, we have modified the funcion index_post in class.postindexeradmin.php and cron.postindexerrebuild.php

I have added :

switch_to_blog($post['blog_id']);
$rssval = get_post_meta($post_id,'rss',true);						restore_current_blog();
if ($rssval == '1') {
....
// Add the post record to the network tables
$this->model->index_post( $post );
....

But it only seems to work when i create tthe post, not when i edit it...

If anyone has a tip i would be really greatful!

Thanks