First, go here to get your code: http://www.google.com/talk/service/badge/New
It will look something like this:
CODE <iframe src="http://www.google.com/talk/service/badge/Show?tk=z01q6amlqv7rdr9hgdsv77rl6i11i3psjimpc8d8gk594de7&w=200&h=60" frameborder="0" allowtransparency="true" width="200" height="60"></iframe> See that big jumble of characters after "Show?tk="? That's your code.
CODE z01q6amlqv7rdr9hgdsv77rl6i11i3psjimpc8d8gk594de7vjed5fe7
You need to get your own code from here and that's what you use to integrate it with your profile. Make sure to exclude the code after the &w=200&h=60. We don't need that.
Next step is easy. Take that code and put it on your profile!

And the Result.

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