Could you explain a bit more what you want your pages to look like? What you're asking doesn't make much sense to me the way I read your question.

I want to let users in a blog comunity to edit their description and there insert javascript.
BUT
I don't want to let users use javascript into post or comments.
I don't want to desactive the html_checker AND security_checker

The question is? Who can I change formatting.php to do that? Is that posible?

(Thanks for your answer)