I don't think I've ever seen Terminal badging in 10.6.*. Or anything earlier, either. And I use Terminal a lot. In fact, it's an Open At Login item and sits in the middle of my Dock, and has been since 10.0.
Google search terms:
mac os terminal badge
The top two results:
http://apple.stackexchange.com/questions/23191/terminal-doesnt-show-badge-how-to-enable
http://apple.stackexchange.com/ques...unts-and-the-dock-icon-bounce-for-terminal-ap
In fact, those seem to be the only really relevant results at all.
Those posts to StackExchange clearly explain what causes Terminal badging (bell characters in output), on what OS version (Lion), and even give an example of how to produce it (sleep 3; printf '\a') on the relevant version of Terminal.
I see nothing at all about badging in Terminal on any other OS version. So off-hand, I'm going to guess "Not possible", but I'm perfectly willing to admit I lacked sufficient google-fu to produce the answer.
Badging isn't something you can do from another process. The process with the badge has to support badging itself. If it doesn't support badging, you can't make it show a badge. To put that in terms of Terminal, only Terminal.app supports badging (or not, before Lion). The processes you run in Terminal.app, like bash or sleep or printf, can only produce output on the pseudo-tty that Terminal itself interprets as a trigger to badge itself. This is a direct consequence of Terminal's support for badging, not something directly caused by those other processes. So without Terminal's ability to recognize bell characters and badge itself, no other process can tell Terminal to badge itself. It would require an in-process extension to do that (security issues), or trickery with Dock.app.