Although TiEmu uses its own format for skin,
it is able to load VTi and old-VTi skins. But, you are strongly
encouraged to use TiEmu skins instead because VTI skin format is
somewhat
limited and doesn't take care of some portability issues (endianess).
How can I develop TiEmu skins or convert them
from VTi?
Julien Blache has developed a multi-platform skin editor, called SkinEdit: