How to Extend Non Extensible Plugins | http://www.ibenic.com/extend-non-extensible-plugins

extend.php

<?php

//... Somewhere in a class that works with hooks

// Get the global Renderer
global $edd_points_render;

// Remove the Old Renderer Methods
remove_action( 'edd_before_purchase_form', 		array( $edd_points_render,'edd_points_guest_user_message' ) );
remove_action( 'edd_before_download_content', 	array( $edd_points_render,'edd_points_message_content' ) );
remove_action( 'edd_before_purchase_form', 		array( $edd_points_render,'edd_points_checkout_message_content' ) );
remove_action( 'edd_before_purchase_form', 		array( $edd_points_render,'edd_points_redeem_point_markup' ) );
remove_action( 'edd_before_purchase_form', 		array( $edd_points_render,'edd_points_buy_points_type_user_message' ) );

$edd_points_render = new HW_Points_Renderer();

// Add enhanced Renderer Methods
add_action( 'edd_before_purchase_form', 		array( $edd_points_render,'edd_points_guest_user_message' ) ); 
add_action( 'edd_before_download_content',		array( $edd_points_render,'edd_points_message_content' ) );
add_action( 'edd_before_purchase_form', 		array( $edd_points_render,'edd_points_checkout_message_content' ) );
add_action( 'edd_before_purchase_form', 		array( $edd_points_render,'edd_points_redeem_point_markup' ) );
add_action( 'edd_before_purchase_form', 		array( $edd_points_render,'edd_points_buy_points_type_user_message' ) );