So, Apple decided to postpone support for shared printers in AirPrint with Mac OS X 10.6.5. But, that doesn’t mean that you can’t get printing to shared printers working with a little 3-file hack.
The hack is simple and easy to perform and will allow you to print from your iOS device running 4.2 to a printer shared from your Mac running 10.6.5 and iTunes 10.1.
You can always enable AirPrint on 10.6.5 the old fashioned way but Netputing has put together AirPrint Hacktivator, a simple application that will do all the heavy lifting for you.
After running the application you may need to restart your computer, delete and re-add your printer in the Print & Fax preference pane but the whole process just takes a few minutes and you’ll be printing from iOS in no time.