You need to get the Ikarus y-adapter cable as per the connection diagram below for JR/Spektrum radios.
The part number for the y-adapter is #31036. You could get it from the following:
http://www.aerofly-5.com/purchase.htm
This JR/Spektrum adapter is also designed for Aerofly and is lower in cost:
http://www.fxaeromodels.com/product_...oducts_id=1659