To enable IPCC (carrier profile) installation on iTunes 8.2:
ON A MAC:
Quit iTunes, open Terminal (Macintosh HD - Applications - Utilities - Terminal) and type or copy/paste the following, then press the RETURN key:
defaults write com.apple.iTunes carrier-testing -bool TRUE
Launch iTunes, select the iPhone in the DEVICES section on the left, hold OPTION and click CHECK FOR UPDATE, then select the IPCC file to apply.
ON WINDOWS:
Quit iTunes, click Start then Run then type or copy/paste the following then press the ENTER or RETURN key:
"C:\Program Files\iTunes\iTunes.exe" /setPrefInt carrier-testing 1
Launch iTunes, select the iPhone in the DEVICES section on the left, hold SHIFT and click CHECK FOR UPDATE, then select the IPCC file to apply.
Octothorpe (irc.osx86.hu #iphone) made this discovery (for Mac OS) at Jun 10 11:05 AM GMT.