I'm not sure about what you want but you can try this :
* draw a rectangular hotspot (begin by the top left corner)
* associate a "display object" (your picture you want to integrate in 3D) in hotspot properties widget
* associate the same picture in "link object"
The picture will be integrated in 3D and will move in center of the screen when clicking.
I believe that what he means by a 'skin' is an image that overlays the panos of the tour - a form of decoration.
You can see an example of such a feature - in this case done with Pano2VR - on this page, look for "Langleite Blomster, Tynset" towards the bottom right of the page:http://tactus360.com/examples.html