Filter that doesn't demand accountability partner?

I'm wondering if anyone knows of a filter that sets a time-frame that you can set yourself but which you can't unlock until the time is up? So if I wanted to have three months as my goal I'd lock it for three months and could not under any circumstances unlock it.

Also, does anyone know how to customize filters so that they allow you to browse for say, a book on pornography addiction, without blocking it as "adult content"?

Look into Pluckeye. It's a free browser addon that works by blocking all image and video files on your browser. You can choose to allow any webpage you want but you set a "delay" for changes to go into effect. That way you can't just allow a pornsite whenever you have cravings. So for example if you have a delay of 3 hours it will take that long before you ate able to view the full page, giving you time to cool off if you are trying to allow a pornsite. There are other more advanced setting as well, such as allowing a site at specified times and "blackout" which will block the internet entirely, good if you have trouble getting off the internet late at night.

Thanks! That's exactly what I was looking for.