Wordpress repository forbids me call wp-load.php in non-WordPress file

Question

I have made a Wordpress Plugin that is a kind of Download Manager. I have a external file download.php that is responsible for making downloads. This file is away of environment Wordpress, for this reason I must called:

$wp_root = dirname(dirname(dirname(dirname(__FILE__))));
require_once $wp_root.'/wp-load.php';

and I can use $wpdb for my sql query.

Note: This file must be external because I use functions "headers()" for force the download.

header("Pragma: public");
header("Expires: 0");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
header("Content-Type: ".$ctype);
header("Content-Length: ".$size);
header("Content-Disposition: attachment; filename=".$info->url_file);
header("Content-Transfer-Encoding: binary");

My plugin works great!, But when I want to publish it on the Wordpress repository, they answered me that it is forbidden to directly call wp-load.php or wp-config.php

Including wp-config.php and / or wp-load.php is not a good idea and we cannot approve a plugin that does so unless it has a very good reason to load the file(s). It is prone to failure since not all WordPress installs have the exact same file structure.

I don't know that use for I can use $wpbd

Note2: For download I first validate it with the DB, then download.

This is my plugin -> http://demo.gopymes.pe/social-godownload/

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Update Sunday 24 febrary 2013

This is getting complicated for me. I can not find documentation on "wp_loaded" so I'm lost with that function.

I tested "template_redirect" but I realized that's not what I want, because redirects the document to download and I do not want the user to know where is located the document to download.

I was reviewing the plugin "DownloadMonitor" and oddly have the same mistake I did, include "wp-load.php" and "wp-login.php" in download.php, however they are in the Wordpress's repository and I do not leave.

Well, keep looking ..

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Update

ok Ok It Works !

I used

add_action('init', 'process');

function process() {
    if(!isset($_GET['goaction'])) return;
    if($_GET['goaction']=='process')
    include("godownload.php");
}

Answer 1

To send HTTP headers just do it early enough. On the action wp_loaded for example. Don’t forget to call exit; when you are done, so WordPress doesn’t send its own headers later.

See also How to Rewrite Wordpress URL for a Plugin