I use ACTion electronics in my own Mersey class and their "dual motor controller board" can "tank steer" without you having to go to the expense of seperate esc's and saves having to use the seond transmitter stick, as the board does it all for you and works a treat.
See the video clip of my boat on this site and you will see how easily it steers off a single stick, as the electronics do all the work.

Modeltugman is right and its simple. There maybe some electronic goodies at ACTion that'll give you more options. ACTion is now run by Componant Shop


http://www.action-electronics.co.uk/ 👍

Hi. it is an easy thing to do really.each ESC will have its own lead and plug,all you have to do is to find out which socket on your received matches the left hand stick on the transmitter,and which matches the right hand stick,then plug the .relevent ESC plug into the corresponding socket for the stick movement that you require