I've created an alternate registration form here: http://forumregistration.simutrans.com/
Please note that this form goes to me personally via email, so I will process your request as soon as I receive the form, which will be quick if I'm around, but slow if I'm not around.
Once I create your account, I will send you the initial password needed to log in. It will be secure and you'll probably want to copy/paste it. Once you're logged in, you can change your password.