Instead of that, maybe look into another solution that can be controlled a bit further? You can always add exceptions, but I don't advise it (who knows if the keylogger isn't malicious?).
I don't know if you have the means, but
http://www.untangle.com is a great way to keep your network clean and secure (and keep the kiddies safe!).
You'll need a dedicated machine to run it on, or a fast windows XP machine to install it on.
There are many other products too, and if you want, you could use
http://www.opendns.com to prevent from accessing malicious / porn / adult sites. This would block you too though, unless you provided different DNS servers for your machine.
As for the exceptions, right-click avast icon in the notification area of your start menu, and click "Program Settings." Then click, "Exclusions." You can then add the program to the exclusion list.
If you're running windows Vista Ultimate, you can use the "Family Safety" (or whatever it's called) program. Windows Live has a comparable product for XP, but it's no where near as configurable as the one in Vista.
(Edited to remove a duplicate word)