HP are notorious for washing their hands of support for what they perceive as older machines, that is when they are not trying to charge for providing support!
I have recently spent a lot of time trying to find a comprehensive driver package for my old-but-still-functional Scanjet 3500 and whilst digging found
this which may or may not be the driver which you have already found.
Google also brings up many sites which purport to offer 4070 drivers but don't know if the feature you require would be included.