Not familiar with the eachine i6, but if it has a trainer out jack there is a good chance it will work.
Chances are you could use the Smartpropolus method described in the manual and in the Spektrum tips document.
There are also other alternatives, dongles such as:
http://www.banggood.com/22-In-1-USB-Flight-Simulat...
or
http://www.banggood.com/IRangeX-FPV-Wireless-Simul...
Hopefully an owner of the eachine i6 can chime in with some more concrete advice.