Sadly not for now. Our company has a solution for that (for some websites), but currently this tool does not have this functionality, since I wanted it be as simple as possible. Maybe in the future.
Some general authentication (like separate input fields for your login credentials on the website) could be potentialy done (but very unsafe for user of the tool, since you would be sending us your credentials as plaintext). But authentication as whole is sadly not as general as semantic data on the web. Not every website has the same login form(different fields), some use captchas, some use authenticators, some do robot checking for too fast logins.
why ? and how would you envisage authentication support to work ? (p.s. awesome tool guy...the clever part is to allow user the ability to describe their process via JavaScript. Hence a perfect DSL (domain specific language))