Publish Category Posts with a future date (modify post.php)

I would like to alter the code in post.php (WP ver 2.2.1), but am not sure exactly how to do it. Here is the bit I want to alter:

559 if ( 'publish' == $post_status ) {
560 $now = gmdate('Y-m-d H:i:59');
561 if ( mysql2date('U', $post_date_gmt) > mysql2date('U',$now) )
562 $post_status = 'future';
563 }

Currently this bit of code checks to see if a post with a status of ‘publish’ has a date in the future. If it does, it changes the status to ‘future’.

What I would like to do is prevent this from happening in the case of a specific category. All categories would operate as normal, EXCEPT the category I select will never be stored in the database as ‘future’, but only as ‘publish’, ‘draft’ or ‘private’.

Any ideas?