I've tried fetching sites from a TYPO3 page using wget following this answer.
But it did not work, since I do not see a target for the login form.
It calls TYPO3FrontendLoginFormRsaEncryption.submitForm() as onsubmit.
I can't show you the website, but I figure this should be common with TYPO3 pages.
Is there a way to get behind the login form?