From https://github.com/wp-e-commerce/WP-e-Commerce/blob/master/wpsc-includes/wpsc-meta-util.php

wpsc-meta-util-example.php

<?php
if ( defined( 'DOING_AJAX' ) && DOING_AJAX ) {

	add_action( 'wp_ajax_wpsc_migrate_anonymous_user', '_wpsc_meta_migrate_anonymous_user_worker' );
	add_action( 'wp_ajax_nopriv_wpsc_migrate_anonymous_user', '_wpsc_meta_migrate_anonymous_user_worker' );

	function _wpsc_meta_migrate_anonymous_user_worker() {

		global $wpdb;

		$blog_prefix = is_multisite() ? $wpdb->get_blog_prefix() : '';
		$key_pattern = "{$blog_prefix}_wpsc_";

		wp_suspend_cache_addition( true );

		$sql = 'SELECT ID FROM '. $wpdb->users . ' WHERE user_login LIKE "\_%" AND user_email = "" AND user_login = user_nicename AND user_login = display_name LIMIT 100';
		$user_ids = $wpdb->get_col( $sql, 0 );

		// Create an array to store users to be removed.
		$bin = array();

		foreach ( $user_ids as $user_id ) {

			$wpdb->query( 'INSERT INTO ' . $wpdb->wpsc_visitors . '(`id`) VALUES ( ' . $user_id . ' )' );

			wpsc_set_visitor_expiration( $user_id,  DAY_IN_SECONDS );

			$meta = get_user_meta( $user_id );
			foreach ( $meta as $key => $value ) {

				if ( strpos( $key, $key_pattern ) === FALSE )
					continue;

				$short_key = str_replace( $key_pattern, '', $key );
				if ( $short_key !== 'cart' ) {
					wpsc_add_visitor_meta( $user_id , $short_key, $value[0] );
				} else {
					$wpsc_user_cart = maybe_unserialize( base64_decode( $value[0] ) );

					if ( ! ($wpsc_user_cart instanceof wpsc_cart) ) {
						$wpsc_user_cart = new wpsc_cart();
					} else {
						continue;
					}
				}
			}

			$comment_count = $wpdb->get_var( 'SELECT COUNT(comment_ID) FROM ' . $wpdb->comments. ' WHERE user_id = ' . $user_id );
			if ( ! count_user_posts( $user_id ) && ! $comment_count ) {
				//wp_delete_user( $user_id );
				// Add user to bin.
				$bin[] = $user_id;
			}
		}

		// Remove users.
		if ( ! empty( $bin ) ) {
			// Convert $bin to string.
			$bin = implode( ',', $bin );
			$wpdb->query( 'DELETE FROM ' . $wpdb->users . ' WHERE ID IN (' . $bin . ')' );
			$wpdb->query( 'DELETE FROM ' . $wpdb->usermeta . ' WHERE user_id IN (' . $bin . ')' );
		}

		wp_suspend_cache_addition( false );
		exit( 0 );
	}

}

add_action( 'wpsc_migrate_anonymous_user_cron', '_wpsc_meta_migrate_anonymous_user_cron' );


function _wpsc_meta_migrate_anonymous_user_cron() {

	global $wpdb;

	set_time_limit( 10 * 60 ); // 10 minutes maximum for the cron

	// WPEC created user records with a funky format,  no email is a dead giveaway, as is login, user name and display name being idnentical with the '_'
	$sql = 'SELECT count( ID ) FROM '. $wpdb->users . ' WHERE user_login LIKE "\_%" AND user_email = "" AND user_login = user_nicename AND user_login = display_name LIMIT 1';
	$ids_to_migrate = $user_ids = $wpdb->get_var( $sql );

	if ( $ids_to_migrate ) {
		$response = wp_remote_post( admin_url( 'admin-ajax.php' ) . '?action=wpsc_migrate_anonymous_user' , array(  'blocking' => true, ) );
		wp_schedule_single_event( time() + 30 , 'wpsc_migrate_anonymous_user_cron' );
	} else {
		wpsc_core_flush_temporary_data();
	}
}