well, yes... both the banner and the forum name *ARE* called out in index.template.php --- but, since those things are set in the admin interface, the code calls for them by variable name.
Editing the code in that file is one way to do what you asked. The only way to duplicate what we have here.
The other methods that I listed will allow you various ways of adding it.
The global headers mod would let yuou add the HTML code directly int he block, and display it.
A portal mod would do the same.
some themes have the option for the icons built in (like the one I linked to, at fx-sabers)