The ‘offset’ parameter does what you want. I’ve written this hack, it should help you…
<?php
//The third parameter corresponds to action priority,
//set it to change the order of execution in case of a conflict
add_action('pre_get_posts', 'the_modified_loop', 10);
function the_modified_loop($query){
//Remove 'is_admin' if you want the code to run for the backend category archive page
if(!is_admin() && $query->is_category()){
$query->set('offset', 3);
}
}
?>
Let me know if it worked!