I was able to use the driver for a HP Officejet 7000 E809a Series that allows me to print up to tabloid format. I don't think I get all the features of the HP 9600, but it is enough for me. Follow the steps at:
http://h10025.www1.hp.com/ewfrf/wc/document?cc=us&dlc=en&docname=c01796821&lc=en