Like Bama said, it might be fine, but it you really need an insulted gound. Wiring ANYTHING for a pool requires the ground to be insulated.
If you go with individual conductors, you will find them on spools back in the electrical department. Just tell the guy back there you want THHN/TWHN, 6 gauge, stranded conductor wire. You want 10 feet of black, 10 feet of red, 10 feet of white, and 10 feet of green.
In you main panel, run the black and red off the 50 amp dipole breaker to the lugs in the Easytouch, run the white from the neutral bus bar in the main, to the neutral bar in the ET, and the ground from the main ground bus bar to the ground bus bar in the ET. Now your all powered up and can add breakers to the ET.