As I'm sure you understand, I agree with Mab about using a script like this, even for a demo page. (Is't security a part of what you wish to demo?
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I couldn't test the login on the demopage (nothing happend when I clicked the login links, found no relevant error except for an XML syntax error and something which might be GeoCities ad-related).
If something works locally, but now when put on a server (and it's not using lots of AJAX or similar) it might be because GeoCities inserts ad-related code here and there, breaking the syntax and disturbing scripts. I've not had time to go through the code line by line, but it would help if you mentioned which error you got, and where.