Automatically create categories

I am currently developing a theme which has a number of categories that are used for positional elements on the homepage. I would like a way of automatically creating these categories for the user when they activate the theme? Is there anyway this is possible?

I’ve tried using wp_insert_category() but this triggers Fatal error: Call to undefined function wp_insert_category(). Any ideas? I’ve even tried replacing my taxonomy.php with the latest version from trac to no avail…