sorry i have no idea what the Robbee Parts look like, so theres not much i can do for you on this one..
logic also tells me that there must be some holes in the chassis to connect the Axel, now wether the steering is done like a rudder, i don't know, but if it was so, then there must be some form of connection on the inside of the chassis were the Axel is fitted in the holes..?
but then again thats "Logic"
my best bet would be to phone the workshops..