Try HP Print and Scan Doctor.
I tried it a while ago and it had errors.
The newer version here : http://h10025.www1.hp.com/ewfrf/wc/document?docname=c03286146&cc=us&dlc=en&lc=en
Found the new Win 8 drivers.
I now have scan in Word and a scanner listed in devices.
The printer is now listed as "HP156E71 (HP Officejet Pro 8600)" instead of "HP Officejet Pro 8600"