The only thing you need is the starter shaft from the original roto start. Clamp it onto the cordless drill and it works like a champ. Just makes sure you don't go to fast and turn down the torque if possible as too much torque may kill the one-way bearing inside.
my buddy did this what he did took the ez start off found a socket to fit the one way bearing then super glued it into the socket make sure its in the right way then he just got an extension to hook up to the the drill then your all set