It isn't the flavor of linux...
The Scanjet 4850 is not supported by any distribution since there is no driver written for the scanner chip used in this device. There is nothing to be done without HP revealing sufficient information, or for somebody with sufficient intelligence, insight and patience to understand enough about the relevant chip, in order for someone to be able to write a driver.
If you need a stand alone scanner, you might look for a Canon Lide 20/30, or HP 5100c/5200c, or one of the other supported scanners on the SANE list .
Otherwise, one of the all-in one machines that is supported by the HPLIP project will give you a scanner along with a printer, but the HPLIP driver will not support a scanner alone.