Any way to print off-center?

Thanks for actually addressing the question. Yes, I have set Custom Layout to 12x18, but I cannot set the border to zero - it is automatically set to a minimum of 0.556" and cannot be reduced. I tried setting a custom paper size of 13x18.5 and was able to set the border to 0.25". My thinking was that this would trick the printer into printing closer to the leading edge of the paper, where the printer's margin is smaller (0.13"). Unfortunately, when I did this, the printer kept giving me "incorrect paper size" errors and refusing to print. The 4000 can print borderless only at the long edges of the paper, not at the leading and trailing edges.
I recall that my Epson 2200 had the same margin issues, but it was possible to override the printer's defaults by using a "borderless" paper setting. With the 4000, this seems not to be possible.
As for color, I am very familiar with color management. I let the app manage color, selected the Ilford profile, perceptual rendering, black point compensation, set print rez at 1440, selected the appropriate media, and turned off color management in the driver. I even tried using absolute rendering, figuring this might lock down the neutrality of the b&w, but no. CS3 still rendered skies ever so slightly cyan, where Aperture was more consistent across the tonal range.
Ultimately, I used QuadTone RIP, a lovely little $50 shareware RIP dedicated to B&W printing. Despite the name, it also works with color inks. Does a terrific job. In daylight, my Aperture/Epson driver prints look very neutral. But, under artificial light, I see a slight reddish cast in midtones. Prints made with QTR are neutral under any light and do not suffer from metamerism.
...'Case anyone's interested.