Thanks figTree7nts,

The link took me to a circuit diagram which shows what connections I need to make.

Instead of connecting esc to Rx each motor connects to its own esc and each esc connects to the mixer which then connects to two channels of Rx.
Not sure yet how Rx picks up its own power supply which it normally does from the esc .... Will be finding out Wednesday so could report back then.

http://ep.yimg.com/ty/cdn/yhst-72470122933521/mixer_p40c.pdf#_ga=1.251803658.207170227.1468802476

Throttle rudder mixer setup, just follow the picture!