How does Stack Overflow support the HTML attribute for authorship (
Are there instructions on ways it can be set up?
According to Google's latest guidelines (and as google goes, so goes the web) you must either put your name and an email on your content, or a link to your google+ profile.
While these can be added to your posts, this is very strongly discouraged. Stackoverflow only supports the user card which links to your stackoverflow profile.
You can put links there to your google+ profile and email, but of course it doesn't do much for your content.
You will need to post a feature request here on meta and propose a solution if you want this to be supported. You'll probably get a lot of push-back about it, so you'll need to argue your point well, rather than relying on links to other websites explaining why to do this. Make sure your arguments are compelling within the context of stackoverflow - how will this help programmers, stack exchange, llc, and others?