Best way to implement temporary website access to users when they need it?

Hi everyone,

We have a web filter in place, but there are times when users may need to temporarily access a website.  What's the best way to do that?

We have tried creating users so they can log in, but that seems to just redirect them so they can change their own filter settings which is not what we want.

The only other way we've seen is the passcode, but that's not temporary.

Is there something we are missing? 

Thanks,

Brandon