It would involve a long username and registering new users here is a pain in the ass.
Theoretically you would be able to get a user's cookie and then redirect that data to an outside site, store the data, and then either let them see they are on the outside site, or redirect them back to the main page of Elite.
Once you have their cookie, then you have their username and password.
Once you have those, you can enter the site as them, change the password, and you have their account to do with as you please.
That said - I think the username would have to be quite long and I suspect that they limit the username length to something well under that limit.
The username would need to look something like:
';a=getCookieCode();redirectCode(a);break;
But the getCookieCode and redirectCode stuff would be much longer than that - were it just the above, I think it would be feasible.
I also don't recall if "break" is the syntax in javascript or if there is something else, but the theory is the same.