[Prop Shaft]

Im still not quite sure what your asking. How many channels are you needing? You can bind 2 receivers to different models on the transmitter and change back and forth.
If your asking how to program the transmitter to make the usable channels do what you want and assign to what switches you want? Then I may be able to help. I just went through this process to get my dx9 to do what I wanted it to. Its probably going to be a similar process for the dx8.
First step is to update the transmitter with the latest firmware. I had to do this in order to access the multi rotor model type. If you already have this type on your transmitter then you shouldnt need to update the firmware. Simply selecting multi rotor model type will allow you to assign any channel to any stick/knob/switch, or whatever. Hope this is a help.