You can use AirPrint Activator as a replacement of the previous generation Hacktivator application. If present, it will take care of cleaning any Apple files installed by the previous generation Hacktivator when you "deactivate" AirPrint. It will only inject a single line in a CUPS configuration when you select to "activate" AirPrint.
What's new in this version:
Fixed a bug with the "Donation" not going away after clicking the "I already donated" button. Should be fine now. Also compiled with the latest Xcode 4 GM release. Result in tighter and faster code (not that it really matter as the application was always pretty small and fast).