I am not a Mac user. But under Windows you find your attached hardware under devices and printers. I believe under mac is the devices. There your dongle should be visible. It should then be calibrated like a game controller (such as a gamepad). There you can also see how many functions are transferred (switch etc) If you have all channels (in my remote control, there are 8 channels) calibrated, then these functions should also work under RC7. If not, then you have to assign the functions such as flaps etc. a key from the keyboard.
But a DX8 with the correct dongle should already be able to transmit 8 channels. In the appendix I have you a few pictures of the procedure under windows attached.
So - first look how many functions you can calibrate under Mac. Then re-calibrate under RC7 and assign the corresponding levers and switches to the functions under advances Channel setup.
otherwise: http://www.aeroflyrc.com/aerofly_rc_7_faq.html
Thanks for all the information I will have to look into into it over the next few days. I will let you know of any progress I make, once again thanks for your time and effort it is appreciated.