NikonPoint

For anyone having this problem, here is the workaround:
Open (untagged) profile target image in CS4.
Edit -> Assign Profile... -> Adobe RGB. Click OK.
File -> Print...
Set Color Handling = Photoshop Manages Colors.
Set Printer Profile = Adobe RGB.
Set Rendering Intent = Relative Colorimetric.
Uncheck Black Point Compensation.

Click Print...

In the Epson driver, disable color management, and choose whatever driver settings you normally want to use for printing on your chosen paper (e.g., 16-bit, appropriate media type, thickness, High Speed = Off, etc.)
Print.

Please note that it does NOT matter that Adobe RGB is used as the profile in the workaround. You could use Pro Photo RGB instead, for example.
It DOES matter that you choose the exact same profile in the “Assign Profile” dialog box and the “Print” dialog box. Make sure that you DO NOT choose “Working RGB-xxxx” as the printer profile.