Using WordPress' parse_request function for dynamic CSS

following a tutorial at http://josephscott.org/archives/2010/03/database-powered-css-in-wordpress-themes/ i'm attempting to use wordpress' parse_request function to include some php-driven CSS... mostly style options occur my theme's options panel. i know that my code looks a bit not the same as the author's, however i attempted it his way already. i'm able to add the

function kia_wp_head() {
  wp_enqueue_style('dynamic', get_bloginfo('stylesheet_directory') . '/admin/ . '?my-custom-content=css');
}
add_action('wp_print_styles', 'kia_wp_head');
//this shows up properly enqueued but when i click on it in source it just brings up a directory listing for the admin folder


function my_custom_wp_request( $wp ) {
    if( isset($_GET['my-custom-content']) && $_GET['my-custom-content'] == 'css'  ) {

        # get theme options
        header( 'Content-Type: text/css' ); ?>

body {
    background-color: <?php echo 'red'; ?>
}

<?php
        exit;
    }
}
add_action( 'parse_request', 'my_custom_wp_request' );

consider the backdrop never turns red-colored, I'm either not applying this correctly or even the tutorial is missing a vital step. i have also attempted another approach to putting the dynamic css in the own custom-css.php file, that is my ultimate goale, however i only agreed to be trying to ascertain if i possibly could communicate with the parse request function correctly:

function my_custom_wp_request( $wp ) {
    if (
        isset($_GET['my-custom-content'])
        && $_GET['my-custom-content'] == 'css'
    ) {
        # get theme options
        header( 'Content-Type: text/css' );
        require dirname( __FILE__ ) . '/custom-css.php';
        exit;
    }
}
add_action( 'parse_request', 'my_custom_wp_request' );

here i am unsure what dirname( FILE ) means exactly, however i also have attempted utilizing a hardcoded path which did not work either.

so how do you get parse_request to determine my php-driven stylesheet?

/* EDIT FOR SOLUTION */

essentially this does not work w/ wordpress_enqueue_style

wordpress_enqueue_style('dynamic', get_bloginfo('stylesheet_directory') . '/admin/ . '?my-custom-content=css')

but Works as referred to at josephscott.org by placing the design and style tag into the mind