HI
I've just had a look on the page.
You found the System Profiler in the ApplicationFolder?When i open the Profiler the windows shows on the left "USB" (under hardware and many other topics like ATA, SCSI and so on)In my opinion, this document of HP lets you only know, if you scanner is connected right.
You'll need a driver in any case. I searched the net and there were are a couples of users who had/have problems with Scanjet4200c and Mac. But maybe this could help you: Go to
www.versiontracker.com and search for VueScan. This is an app. for mac which should be working with a lot of scanners.
(btw versiontracker.com is very good site for useful applications, updates, new trials and so on)
I hope, this could help you a little bit
cu, dani_mac