Call web-service from on screen form guide



Is it possible for a Web Service to alter the fields on a Form Guide that is presently on screen??

I'd like the user to be presented with the form guide, they enter in one (or two membership numbers) and press a button that is displayed on the form guide. Can this button have javascript behind it to call a web service, passing it the one/two membership numbers, and return personal data for these one/two members and for this data to be displayed to the user on the form guide ??