Judging by
this page from Apple's website, it doesn't appear that your ScanJet is supported under 10.6. Have you run Software Update to check, just in case? This is the procedure according to that page:
To get software for printers that were not installed during the Mac OS X installation process, choose Software Update from the Apple menu, allow it to complete the process of "Checking for new software", and then connect your printer or add it using the Print & Fax pane of System Preferences. If software for your printer is available through Software Update, you will see a prompt asking if you would like to download and install this software.