Hi skiziks,
I understand you aren't able to use the HP Scan Software on the 10.8.
I will be happy to help you.
There are no Full Feature Software for the 10.8, so the HP Scan won't work properly.
Did you upgrade from 10.7 to have the HP Scan Software?
I have provided a document for How to Scan: OS X v10.8 through Apple's Software.
Hope this helps.
Thank you for posting on the HP Forums.
Have a nice day!