How to apply category to link (bookmark, not hyperlink)?

I am building a plugin. It successfully inserts a row to the $wpdb->links table, thus it now has the link’s insert ID. I now need it to add the link to one of the existing link categories, but not via the Link Manager; it needs to be done silently by the plugin. Is there a function that will do this, or do I need to write some SQL to create the relation in the terms, term_taxonomy, term_relationships tables?