You need something called hpoj (maybe ptal). First install those packages with that YAST thing. I assume you have a PSC 750. Make sure the sane and xsane packages are installed too.
Then open a console, switch on your PSC and type
there will be a "wizard" guiding you. At the end the program should detect your printer. Then type:
Here make sure that at the end of the file the line "hpoj" is uncommented (no # sign). Otherwise uncomment and save. Maybe the file dll.conf is located somewhere else. In this case find it and change the "kwrite" line above accordingly.
Reboot your machine. During the boot, check if ptal is started. Otherwise find how to start services in Suse.
Finally, launch Kcontrol and go to "printers". Select your PSC 750 and open the part where you can change interfaces (USB, Parallel, network, etc.). Do NOT select USB printer but "other interface" (don't remember the exact term, but you will find it). Then you will have to choose from a list the "ptal mlc:****" entry . If you don't do that, you won't be able to print any more!
Check if everything works by launching XSane, it should detect the scanner now.