my procedure:

+open
+file -> skin editor
+edit -> select all
+edit -> set skin
+add another skin and add its texture
+next skin (arrow down)
+pick "skin1" and set skin = skin changes in preview window to the second skin
+file -> import skin mapping (import from the second uv-mapping textfile)

The uv layout changes, but it changes the mapping for all layers of the skin. skin0 and skin1 now have the same uvw-map (the changed one)

I am not sure what you mean by "swop skin sets of the model".


cheers