Just in case this of interest to others it seems this is possible, (and thanks to Kevin for his prompt response on this).
The Press Release in the WCM example uses exactly this feature to allow users to of the press release (PR) xform to select from a dynamically generated list of available company footers. The PR XForm uses a callout to the "get_company_footer_choices_simple_type.jsp" to present the users with a dynamically generated list of the currently available footers which the user can select one or more of.