What’s the proper way to include inlined javascript-source?

To print JavaScript code to your page, you have several paths to choose from. The most obvious would be the wp_footer action. Just hook a function to it and make it print your JavaScript/jQuery code, wrapped in <script /> tags.

// EDIT
As an addition, if your custom JavaScript/jquery code is static (i.e., there are no dynamic parts in it), you should put it in a separate JS file and enqueue it with the lib as dependency. But you explicitly asked for printing so that’s what I answered.

As for your comment, as long as your code doesn’t have to be executed before the page has been rendered—which doesn’t seem to be the case, according to your question (document.ready)—this is just best practice to enqueue script files in the footer.