Ok, in your fetch folder open posts.php
$CFG['posts_hide_normal'] = false;
$CFG['posts_hide_normal'] = true;
Now normal posts won't be displayed.
By setting the option below to false
you make it display stickies.
$CFG['posts_hide_sticky'] = false;
By setting the announcements option to true you hide the announcements and thereby force the page only to pull sticky threads.
$CFG['posts_hide_announcements'] = true;
What I suggest you do is use stickies to determine front page threads, then set normal to true, announcements to true and sticky to false.
Now you can determine a front page topic from the posting page by making it sticky.