From what I have been able to gather, it would seem that printing from SN with CS4 using a valid profile and an older Epson driver (non-SL) results in a print that is NOT color managed.
I is not that it is NOT color managed it is more like Double color managed.
Which brings up an idea that I have yet to test, but here is what I was thinking of trying. Convert to the printer profile in PSCS4 and then assign sRGB, AdobeRGB, or Generic RGB and then print with Printer Manages Color. The idea being that there is a profile applied in the driver by colorsync, but which one. Seems if we could know which one is being applied/converted by colorsync then sending a print with that assigned profile would negate any conversion that colorsync is doing.
PS: Just did a preliminary test of this and it looks like Generic RGB is the one to assign. I must say I got a pretty good print. Now I think one should be able to assign Generic RGB to an unmanaged target and be able to print a correct profiling target from PSCS4 to the 3.09 7600 and 9600 driver in Snow Leopard.
Update: I did a test printing unmanaged targets from ID and from PS. The targets match if you assign sRGB in PS. They did not match with Generic RGB. Will read targets later, create a profile, test and report back.