Change DataProvider source via WebiServices.document in Webi UI Extensions ?

Hi,

I'd like to be able to build something into WebI via Web Intelligence UI Extension Points, that can change a dataprovider for a report from one Universe to another Universe (unv to unx in this case)

I know it's possible via RESTful Web Services, but I'd like to do it from within an Extension.

The documentation for 4.1 shows a WebIntelligence Service JavaScript method WebiServices.document.updateDataProvider but it doesn't seem to take an argument for a new UniverseId.

Is there another way to do this via the JavaScript API ?  If not is this something that might be added to the WebIntelligence Service JavaScript API in 4.2 ?

If the answer to both of these is no, is there a way of accessing the RESTful Web Services calls from within the WebIntelligence Service JavaScript API without having to make another call to create a session etc ?

Thanks,

Hayden