if it fails im running out of ideas...
One thing might be that perhaps epson are not installing a CUPS printer driver on your mac by default.
You might have to try Gutenprint, which has open source CUPS drivers for OS X & the Epson TX400
http://gimp-print.sourceforge.net/
Then try the os X printer install
http://support.apple.com/kb/HT3049
And use the CUPS driver.
One thing might be that perhaps epson are not installing a CUPS printer driver on your mac by default.
You might have to try Gutenprint, which has open source CUPS drivers for OS X & the Epson TX400
http://gimp-print.sourceforge.net/
Then try the os X printer install
http://support.apple.com/kb/HT3049
And use the CUPS driver.