I wanted to make a way to use the new Stems format without buying equipment, so I made a two deck stems controller for the iPad.  This is setup to use decks C and D as the Stems decks, as I use DVS for decks A and B.  Both decks are controlled on one page, because I hate flipping through tabs to get different decks.  If I get enough requests, I can redo this to have different pages or use decks A and B.  Labels for what things do are on the right side.  You will have to import the .tsi file into Traktor and the OSC file into your iPad to use.