Thank you Edward!
Your procedure works GREAT!
Here is an update to your procedure for those who are:
Running - MAC OS x Version 10.5.5 and
Have – HP PSC 2210xi All-In-One printer
First, get the software for HP PSC 2200 Series – MAC OS X v10.3 and v10.4 (Universal)
http://h10025.www1.hp.com/ewfrf/wc/softwareDownloadIndex?softwareitem=mp-42265-1 &lc=en&dlc=en&cc=us&product=79502&os=219
Then mount the dmg: 2200
790EN.dmg and launch the installer. There were no error messages when I installed this app. The software found the printer but not the scanner.
Then follow the remainder of Edward’s procedure:
Get the software for DeskJet F4280 AIO.
http://h10025.www1.hp.com/ewfrf/wc/softwareDownloadIndex?softwareitem=mp-58668-1 &lc=en&cc=us&os=219&product=3390949&dlc=en
Mount the dmg: HP
Installer_DJF4200v9.7.1.dmg and launch, it will ask you for the device, select "device not listed" but the second time it ask you to pick a device shown as listed, pick the only one shown then continue to finish installing... when done. It will attempt to start the HP Setup Assistant. It won't find the PSC at all so quit the HP Setup Assistant
Then go to HP folder inside the application directory and then open Device Utilities and drag "HP Setup Assistant" to desktop or to trash but don't empty it yet.
Then back to 2200
790EN.dmg and mount it and don't run the installer but do "Show Package Contents" then open "Contents then "Sub Installers" then "Setup" then run the "Setup" installer
It will install the HP Setup Assistant is specific for 2210xi not the F4280.
When done, quit the installers. You may trash the HP Setup Assistant that is on desktop and empty it.
Then go to HP folder then open Device Utilities folder and run HP Setup Assistant, it will find the 2210xi and continue finishing setting up. Now you have Leopard compatible software! Now try HP Scan Pro and enjoy!
NOTES:
The scan button on the HP PSC 2210xi All-In-One printer works properly.
This procedure will also add a printer named HP PSC 2200 Series-1. Use this printer, I have found that everything works properly.