Example Iron-Ajax Usage. This file goes in mu-plugins and generates /wp-content/seo-spec-sheet-export.csv with the exported information.

seo-spec-sheet-export.php

<?php
/*
 * Export old spec sheet Permalinks and slug for SEO population on new site
 * 2014-12-15
 */
add_action( 'plugins_loaded', array( 'Fe_Export_Seo', 'init' ) );

class Fe_Export_Seo {
	public static function init() {
		if ( class_exists( 'Fe_Ajx' ) ) {
			new Fe_Ajx( array(
				'instance_id' => 'Export SEO Links',
			) );
		}

		add_filter( 'fe_ajx_export_seo_links_entries_count',
			array( __CLASS__, 'entries_count')

		);
		add_filter( 'fe_ajx_export_seo_links_process',
			array( __CLASS__, 'process'),
			10,
			2
		);
	}

	public static function entries_count( $count ) {
		$output_line = array(
			'post_id',
			'Permalink',
		);
		self::write_to_csv( $output_line );


		$args = self::get_query_args();

		$fe_query = new WP_Query( $args );

		$count = $fe_query->found_posts;
		wp_reset_postdata();
		return $count;
	}

	public static function process( $result, $index ) {
		$output_line = array();

		$args = self::get_query_args();
		$args['offset'] = $index;

		$fe_query = new WP_Query( $args );

		if ( $fe_query->have_posts() ) {
			$fe_query->the_post();
			$permalink = get_the_permalink();
			$output_line = array(
				get_the_ID(),
				$permalink,
			);
			self::write_to_csv( $output_line );
		}

		wp_reset_postdata();
		return $result;
	}

	public static function write_to_csv( $line ) {
		$fp = fopen( WP_CONTENT_DIR . '/seo-spec-sheet-export.csv', 'a' );
		fputcsv( $fp, $line );
		fclose( $fp );
	}

	public static function get_query_args() {
		return array(
			'posts_per_page' => 1,
		);
	}
}