Answering My own question..

function custom_permalink( $permalink, $post ) {
    // Get the categories for the post
    $post       = get_post( $post_id );
    $category   = get_the_category( $post_id ); 
    $post_year  = mysql2date("Y", $post->post_date);
    $target_cat = 6; // Category we\'d like to change permalink for

    if ( empty( $post_year ) ) return $permalink;

    if ( $category[0]->cat_ID == $target_cat ) {
        $permalink = trailingslashit( home_url( $category[0]->slug . \'/\' .$post_year .\'/\' . $post->post_name . \'/\'  ) );
    }

    return $permalink;
}

add_filter( \'post_link\', \'custom_permalink\', 10, 2 );