On MAC's there is a page length limit of either aprox 44 inch or 90 inch depending on the driver.
The way to overcome this and print long images is to use an application that supports tileing such as Illustrator.
Another way is to try the pageproofer EX trial version available for download from www.epson.co.uk
it is in the support/drivers and downloads for the new K3 ink printers (Photo 2400, Pro4800, Pro 7800 and Pro 9800), this has an inbuilt tileing for banners based on standard paper sizes and with the new K3 drivers sets the driver up automatically for you. With the older printer drivers you will have to make sure that you are using the banner driver and that the save roll paper option is checked in the roll paper setup.