I would hire Philip if your not sure otherwise,
Look back on page 39 of this thread and you will see how i have done it. Using the method i describe there all you are doing is making an override for the worldpay callback pages, namely the success page and failure or cancelled page. If you use the override then if worldpay do put the href back into the whitlist then just delete the folder and nothing in Philips module has been touched but if they don't put the href in then you can customise those 2 pages using the override and it will not effect any of your other zencart pages. You do have to hard code a couple of url's but nothing too dificult.
Lake



