I needed the ability to exclude certain posts from the generated list so here is what I modified:
in list_cat_posts.php:
added another parameter on line 42:
41 'exclude' => '0',
42 'excludeposts' => '0'
43 ), $atts);
and on line 57 (now line 58):
57 '&order=' . $atts['order'] .
58 '&exclude=' .$atts['excludeposts']);
59
60 //Template code:
Now, all one has to do is add excludeposts=5,15,124 in the list of parameters for catlist and posts with ids 5, 15 and 124 will be excluded.
Cheers!