According to
www.linuxprinting.org, the Epson CX6400 works "Mostly". Unfortunately, the CX6600 is not listed, but try using the driver for the CX6400.
You should set the printer up by pointing your browser to
http://localhost:631 and selecting "Manage Printers" and then "Add Printer"
I hope this helps
--Ian
PS: Welcome to LQ!