If you have the original hotwire you need a OTG cable. You you have the new gen2 hotwire you don't need otg but you still need mini to micro USB cable.
Took 2 weeks from china (free shipping) but your waiting for the update anyway.
http://www.amazon.com/gp/aw/d/B005QX7KYU

They will be updating the app soon to work with the gen1 esc's, but for now it only works on gen2.

The newer android firmware will not work until the update is released, for now only 4.1 works, 4.2+ does not.

There's a thread about it in the electric offroad forum with tons of info
http://www.rctech.net/forum/electric...-new-post.html