How to control which cookies are used.

[nerbert]

I'm working on a project that requires a separate login with a password different from the usual forum one. Since the browser automatically fills in the password input on any login form with the usual one, I want to read a cookie and fill the special password in with JavaScript. The trouble is that the password cookie is among the request cookies when the form is submitted, as well as in other pages in my project. I've looked at regular forum pages and they don't show the cookie there (showthread for instance).

So how do you control which cookies are listed in the request for various pages? The cookie for the special password is used only on the browser to fill in the password input and is not read by the server scripting.