Does Imageprint let you define a custom paper size? Using Qimage and roll paper on my 4800 I just define a paper size like 17x24, set the source as roll, and go.
Yep, same idea. Set up a user defined page size (17 x whatever), then uncheck Sheet in the IP Printer setup dialog box, and make sure the Auto Cut check box matches the roll/sheet setting on the 4800 panel. That's really all there is to it.