Despite both Epson and Apple's technical support saying that there is no solution under OS X 10.5, I have got it working!
The problem was that the Mac version of the PPD file contains some illegal characters (as confirmed using the PPD checker at www.cups.org). The solution therefore was to...
Have created a temporary workaround...have brought an old Mac back into service with Tiger 10.4 running on it that hapilly lets me install the correct PPD. I then share that printer on the network and all the 10.5 machines can print via the 10.4 mac to the rip server to the SC3000. Not exactly...
Have just upgraded from Tiger to Leopard, but I can no longer access the print driver for our EPSON Stylus Color 3000 using the Epson StylusRIP. I can see the RIP server ok and it has installed as a printer. However neither of the two PPDs it finds (Gutenprint v5.1.3 and Gimp-Print v5.0.0-beta2)...