I\'m trying to autosubmit a form with greasemonkey however I\'m not sure how to do it with this button. The button seems to have the following properties
a class
document.getElementsByTagName('form')[0].submit();
Note that this will only work if the first form on the page. You can increase the array index to [1] if you need to, or loop through the array looking for the right form.
After you have got the username and password fields filled in, do this:
unsafeWindow.Form.submit(document.getElementsByClassName('submit')[0]);
Check unsafeWindow
documentation here.