I don;t use Wings so this is only a supposition, but a method that might work would be to export the object, load it into UVMapper, export the UV information, Select All in UVMapper and assign all to a single group. Save the object file, load it into Wings and do the morph then save the object again. Load the object into UVMapper and load the saved UV information, save the object and load it in as a morph via Morphloader.

Again, since I don;t use Wings I have no way of testing this so it may not work, but it seems a logical method. It;s not as straight forward and easy as using Morphloader one of the listed deformer programs but may be a work around. Perhaps someone with Morphloader and Wings could give it a try.