AirPrintFix adds firewall rules to fix USB printing over (older 802.11b&g) AirPort Express and AirPort Extreme.
The fix simply adds a firewall rule that limits comms on port 10000 -- that's the AirPort usb -- to 12Mbit/s -- that's USB 1.1 speed.
The dearchived file is a StartUpItem. Place it in /Library/StartUpItems and reboot two times; first time you should be asked for permission to fix permissions on the startupitem, second time will install the firewall rule. Of course, only do this if you are sure you want too.
Thanks to BFA who has reminded me of the MacOSXHints hints that I posted at:
which has some history of the fix. AirPrintFIx tries to make the fix last through a reset.