Although ATS does leverage Selenium Webdriver, it is not possible to trigger complete Selenium scripts, like importing existing scripts from another tool. However, it is possible to a certain extent to execute Selenium-like actions. So you can find elements by CSS/XPath/Sizzle/etc., click them, send text, make assertions, etc. However, the strength of ATS lies in the fact that you don't NEED to do all this for most of the things you want to achieve. Only in specific cases do you need to use this. But if you need it, or if you want to, t=you can use these types of actions.