iChat, AIM & HTML

Ultimate solution for disabling HTML in iChat AIM accounts. Works in Lion.

Run Terminal, execute this:

defaults read com.apple.iChat.AIM|sed "s/\(ForceICQPlainText\).*/\1 = 1;/"|xargs -0 defaults write com.apple.iChat.AIMchflags uchg Library/Preferences/com.apple.iChat.AIM.plist

Reboot and run Terminal again, execute:

chflags nouchg Library/Preferences/com.apple.iChat.AIM.plist

Review AIM account settings (mostly ports).
...
Profit!