I think you will have to directly access the selenium-webdriver driver (if browseryour watir-webdriver is your browser):
browser.driver
To get the selenium-webdriver underline element for the watir-webdriver element, use wd(assuming that elementis your watir-webdriver element that you want to click):
element.wd
Combining all this, you would do:
browser.driver.action.move_to(element.wd, 30, 0).click.perform