Router based web redirect rather than block?

Alright, so I’ve got a fairly complicated network setup in my home (I made it more complicated because… well I wanted to) and I’m tired of the “children” going on myspace and screwing with stuff… Actually it has nothing to do with that. They’re little pricks and instead of doing their homework they waste their time on there. They know nothing about anything. I’ve seen gorillas that could form more cognizant sentences than them. Regardless, I want to setup the router to redirect them to a page rather than outright blocking it using access restrictions. I use dd-wrt firmware and was curious if this was even possible. I know how to use iptables and the such as well so if you have a super nerdy answer go with it, I’ll probably be able to grasp it. Thanks.