s2member woocommerce hooks

I am setting up a site with s2member and woocommerce. I would like to have the checkout fields for woocommerce be auto populated with the s2member custom fields.

I have the code below now (for testing) and it will display the WP fields just fine. How do I add to this code so that it will pull the custom fields from s2member (for example I have one called “address”.

Thanks,
biorn

// Hook in
add_filter( 'woocommerce_checkout_fields' , 'custom_override_checkout_fields' );

// Our hooked in function - $fields is passed via the filter!
function custom_override_checkout_fields( $fields ) {
	$current_user = wp_get_current_user();

     $fields['billing']['billing_first_name']['default'] = $current_user->user_firstname;
	 $fields['billing']['billing_last_name']['default'] = $current_user->user_lastname;
     return $fields;
}

https://wordpress.org/plugins/s2member/