How to include wp-load.php from any location?

Question

I have a plugin which calls a stand-alone php script (myAjax.php) via a jQuery.ajax() script inside the plugin.

I need to place the following code into the myAjax.php file:

require_once('../../../wp-load.php');

if (!is_user_logged_in()){
    die("You Must Be Logged In to Access This");
}
if( ! current_user_can('edit_files')) {
    die("Sorry you are not authorized to access this file");
}

However, I'd like a more bulletproof method of specifying the path to wp-load.php in case the actual relative path is different than my example.

Answer 1

To add to what Milo said, here are 2 great posts on the subject.
http://www.garyc40.com/2010/03/5-tips-for-using-ajax-in-wordpress/
http://ottopress.com/2010/dont-include-wp-load-please/

Also for the sake of learning, the first slideshow http://andrewnacin.com/2011/04/16/wordcamp-seattle/

Answer 2

Don't. Use AJAX the proper WordPress way.